diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/History/History.qml b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/History/History.qml
index e1e527d..85abbc7 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/History/History.qml
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/History/History.qml
@@ -212,8 +212,11 @@ Item {
     }
     
     Component.onCompleted: {
-        Modules.History.history = historyObj
-        Modules.History.themeTextColor = sysPalette.windowText
-        Modules.History.imageDepth = Screen.devicePixelRatio
+        Modules.History.initialize({
+            historyObj,
+            themeTextColor: sysPalette.windowText.toString(),
+            imageDepth: Screen.devicePixelRatio,
+            fontSize: 14
+        })
     }
 }
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml
index 4159497..e54781f 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml
@@ -120,12 +120,6 @@ Canvas {
     */
     property bool showygrad: false
     
-    /*!
-       \qmlproperty int LogGraphCanvas::maxgradx
-       Max power of the logarithmic scaled on the x axis in logarithmic mode.
-    */
-    property int maxgradx: 90
-    
     /*!
        \qmlproperty var LogGraphCanvas::imageLoaders
        Dictionary of format {image: [callback.image data]} containing data for defered image loading.
@@ -139,14 +133,14 @@ Canvas {
     
     Component.onCompleted: {
         imageLoaders = {}
-        Modules.Canvas.initialize(canvas, drawingErrorDialog)
+        Modules.Canvas.initialize({ canvas, drawingErrorDialog })
     }
     
     Native.MessageDialog {
         id: drawingErrorDialog
         title: qsTranslate("expression", "LogarithmPlotter - Drawing error")
         text: ""
-        function showDialog(objType, objName, error) {
+        function show(objType, objName, error) {
             text = qsTranslate("error", "Error while attempting to draw %1 %2:\n%3\n\nUndoing last change.").arg(objType).arg(objName).arg(error)
             open()
         }
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/Settings.qml b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/Settings.qml
index c94bef1..3c6e994 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/Settings.qml
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/Settings.qml
@@ -128,7 +128,7 @@ ScrollView {
     property string saveFilename: ""
     
     Component.onCompleted: {
-        Modules.IO.initialize(root, settings, alert)
+        Modules.IO.initialize({ root, settings, alert })
     }
     
     Column {
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/canvas.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/canvas.mjs
index 020ff88..04abf68 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/canvas.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/canvas.mjs
@@ -17,30 +17,28 @@
  */
 
 import { Module } from "./common.mjs"
+import { FUNCTION, Interface, CanvasInterface, DialogInterface } from "./interface.mjs"
 import { textsup } from "../utils.mjs"
 import { Expression } from "../math/index.mjs"
 import Latex from "./latex.mjs"
 import Objects from "./objects.mjs"
 import History from "./history.mjs"
 
-
 class CanvasAPI extends Module {
-
     constructor() {
-        super('Canvas', [
-            Modules.Objects,
-            Modules.History
-        ])
+        super("Canvas", {
+            canvas: CanvasInterface,
+            drawingErrorDialog: DialogInterface
+        })
 
-        /** @type {HTMLCanvasElement} */
+        /** @type {CanvasInterface} */
         this._canvas = null
 
         /** @type {CanvasRenderingContext2D} */
         this._ctx = null
 
         /**
-         * @type {Object}
-         * @property {function(string, string, string)} showDialog
+         * @type {{show(string, string, string)}}
          * @private
          */
         this._drawingErrorDialog = null
@@ -62,86 +60,132 @@ class CanvasAPI extends Module {
         }
     }
 
-    initialize(canvasObject, drawingErrorDialog) {
-        this._canvas = canvasObject
+    /**
+     * Initialize the module.
+     * @param {CanvasInterface} canvas
+     * @param {{show(string, string, string)}} drawingErrorDialog
+     */
+    initialize({ canvas, drawingErrorDialog }) {
+        super.initialize({ canvas, drawingErrorDialog })
+        this._canvas = canvas
         this._drawingErrorDialog = drawingErrorDialog
     }
 
-    get width() { return this._canvas.width }
+    get width() {
+        if(!this.initialized) throw new Error("Attempting width before initialize!")
+        return this._canvas.width
+    }
 
-    get height() { return this._canvas.height }
+    get height() {
+        if(!this.initialized) throw new Error("Attempting height before initialize!")
+        return this._canvas.height
+    }
 
     /**
      * Minimum x of the diagram, provided from settings.
      * @returns {number}
      */
-    get xmin() { return this._canvas.xmin }
+    get xmin() {
+        if(!this.initialized) throw new Error("Attempting xmin before initialize!")
+        return this._canvas.xmin
+    }
 
     /**
      * Zoom on the x-axis of the diagram, provided from settings.
      * @returns {number}
      */
-    get xzoom() { return this._canvas.xzoom }
+    get xzoom() {
+        if(!this.initialized) throw new Error("Attempting xzoom before initialize!")
+        return this._canvas.xzoom
+    }
 
     /**
      * Maximum y of the diagram, provided from settings.
      * @returns {number}
      */
-    get ymax() { return this._canvas.ymax }
+    get ymax() {
+        if(!this.initialized) throw new Error("Attempting ymax before initialize!")
+        return this._canvas.ymax
+    }
 
     /**
      * Zoom on the y-axis of the diagram, provided from settings.
      * @returns {number}
      */
-    get yzoom() { return this._canvas.yzoom }
+    get yzoom() {
+        if(!this.initialized) throw new Error("Attempting yzoom before initialize!")
+        return this._canvas.yzoom
+    }
 
     /**
      * Label used on the x-axis, provided from settings.
      * @returns {string}
      */
-    get xlabel() { return this._canvas.xlabel }
+    get xlabel() {
+        if(!this.initialized) throw new Error("Attempting xlabel before initialize!")
+        return this._canvas.xlabel
+    }
 
     /**
      * Label used on the y-axis, provided from settings.
      * @returns {string}
      */
-    get ylabel() { return this._canvas.ylabel }
+    get ylabel() {
+        if(!this.initialized) throw new Error("Attempting ylabel before initialize!")
+        return this._canvas.ylabel
+    }
 
     /**
      * Width of lines that will be drawn into the canvas, provided from settings.
      * @returns {number}
      */
-    get linewidth() { return this._canvas.linewidth }
+    get linewidth() {
+        if(!this.initialized) throw new Error("Attempting linewidth before initialize!")
+        return this._canvas.linewidth
+    }
 
     /**
      * Font size of the text that will be drawn into the canvas, provided from settings.
      * @returns {number}
      */
-    get textsize() { return this._canvas.textsize }
+    get textsize() {
+        if(!this.initialized) throw new Error("Attempting textsize before initialize!")
+        return this._canvas.textsize
+    }
 
     /**
      * True if the canvas should be in logarithmic mode, false otherwise.
      * @returns {boolean}
      */
-    get logscalex() { return this._canvas.logscalex }
+    get logscalex() {
+        if(!this.initialized) throw new Error("Attempting logscalex before initialize!")
+        return this._canvas.logscalex
+    }
 
     /**
      * True if the x graduation should be shown, false otherwise.
      *  @returns {boolean}
      */
-    get showxgrad() { return this._canvas.showxgrad }
+    get showxgrad() {
+        if(!this.initialized) throw new Error("Attempting showxgrad before initialize!")
+        return this._canvas.showxgrad
+    }
 
     /**
      * True if the y graduation should be shown, false otherwise.
      * @returns {boolean}
      */
-    get showygrad() { return this._canvas.showygrad }
+    get showygrad() {
+        if(!this.initialized) throw new Error("Attempting showygrad before initialize!")
+        return this._canvas.showygrad
+    }
 
     /**
      * Max power of the logarithmic scaled on the x axis in logarithmic mode.
      * @returns {number}
      */
     get maxgradx() {
+        if(!this.initialized) throw new Error("Attempting maxgradx before initialize!")
         return Math.min(
             309, // 10e309 = Infinity (beyond this land be dragons)
             Math.max(
@@ -156,6 +200,7 @@ class CanvasAPI extends Module {
     //
 
     requestPaint() {
+        if(!this.initialized) throw new Error("Attempting requestPaint before initialize!")
         this._canvas.requestPaint()
     }
 
@@ -163,6 +208,7 @@ class CanvasAPI extends Module {
      * Redraws the entire canvas
      */
     redraw() {
+        if(!this.initialized) throw new Error("Attempting redraw before initialize!")
         this._ctx = this._canvas.getContext("2d")
         this._computeAxes()
         this._reset()
@@ -171,7 +217,7 @@ class CanvasAPI extends Module {
         this._drawLabels()
         this._ctx.lineWidth = this.linewidth
         for(let objType in Objects.currentObjects) {
-            for(let obj of Objects.currentObjects[objType]){
+            for(let obj of Objects.currentObjects[objType]) {
                 this._ctx.strokeStyle = obj.color
                 this._ctx.fillStyle = obj.color
                 if(obj.visible)
@@ -202,12 +248,12 @@ class CanvasAPI extends Module {
             x: {
                 expression: exprX,
                 value: x1,
-                maxDraw: Math.ceil(Math.max(Math.abs(this.xmin), Math.abs(this.px2x(this.width)))/x1)
+                maxDraw: Math.ceil(Math.max(Math.abs(this.xmin), Math.abs(this.px2x(this.width))) / x1)
             },
             y: {
                 expression: exprY,
                 value: y1,
-                maxDraw: Math.ceil(Math.max(Math.abs(this.ymax), Math.abs(this.px2y(this.height)))/y1)
+                maxDraw: Math.ceil(Math.max(Math.abs(this.ymax), Math.abs(this.px2y(this.height))) / y1)
             }
         }
     }
@@ -216,14 +262,14 @@ class CanvasAPI extends Module {
      * Resets the canvas to a blank one with default setting.
      * @private
      */
-    _reset(){
+    _reset() {
         // Reset
         this._ctx.fillStyle = "#FFFFFF"
         this._ctx.strokeStyle = "#000000"
         this._ctx.font = `${this.textsize}px sans-serif`
-        this._ctx.fillRect(0,0,this.width,this.height)
+        this._ctx.fillRect(0, 0, this.width, this.height)
     }
-    
+
     /**
      * Draws the grid.
      * @private
@@ -233,18 +279,18 @@ class CanvasAPI extends Module {
         if(this.logscalex) {
             for(let xpow = -this.maxgradx; xpow <= this.maxgradx; xpow++) {
                 for(let xmulti = 1; xmulti < 10; xmulti++) {
-                    this.drawXLine(Math.pow(10, xpow)*xmulti)
+                    this.drawXLine(Math.pow(10, xpow) * xmulti)
                 }
             }
         } else {
-            for(let x = 0; x < this.axesSteps.x.maxDraw; x+=1) {
-                this.drawXLine(x*this.axesSteps.x.value)
-                this.drawXLine(-x*this.axesSteps.x.value)
+            for(let x = 0; x < this.axesSteps.x.maxDraw; x += 1) {
+                this.drawXLine(x * this.axesSteps.x.value)
+                this.drawXLine(-x * this.axesSteps.x.value)
             }
         }
-        for(let y = 0; y < this.axesSteps.y.maxDraw; y+=1) {
-            this.drawYLine(y*this.axesSteps.y.value)
-            this.drawYLine(-y*this.axesSteps.y.value)
+        for(let y = 0; y < this.axesSteps.y.maxDraw; y += 1) {
+            this.drawYLine(y * this.axesSteps.y.value)
+            this.drawYLine(-y * this.axesSteps.y.value)
         }
     }
 
@@ -260,10 +306,10 @@ class CanvasAPI extends Module {
         let axisypx = this.x2px(axisypos) // X coordinate of Y axis
         let axisxpx = this.y2px(0) // Y coordinate of X axis
         // Drawing arrows
-        this.drawLine(axisypx, 0, axisypx-10, 10)
-        this.drawLine(axisypx, 0, axisypx+10, 10)
-        this.drawLine(this.width, axisxpx, this.width-10, axisxpx-10)
-        this.drawLine(this.width, axisxpx, this.width-10, axisxpx+10)
+        this.drawLine(axisypx, 0, axisypx - 10, 10)
+        this.drawLine(axisypx, 0, axisypx + 10, 10)
+        this.drawLine(this.width, axisxpx, this.width - 10, axisxpx - 10)
+        this.drawLine(this.width, axisxpx, this.width - 10, axisxpx + 10)
     }
 
     /**
@@ -276,38 +322,38 @@ class CanvasAPI extends Module {
         // Labels
         this._ctx.fillStyle = "#000000"
         this._ctx.font = `${this.textsize}px sans-serif`
-        this._ctx.fillText(this.ylabel, axisypx+10, 24)
+        this._ctx.fillText(this.ylabel, axisypx + 10, 24)
         let textWidth = this._ctx.measureText(this.xlabel).width
-        this._ctx.fillText(this.xlabel, this.width-14-textWidth, axisxpx-5)
+        this._ctx.fillText(this.xlabel, this.width - 14 - textWidth, axisxpx - 5)
         // Axis graduation labels
-        this._ctx.font = `${this.textsize-4}px sans-serif`
+        this._ctx.font = `${this.textsize - 4}px sans-serif`
 
-        let txtMinus = this._ctx.measureText('-').width
+        let txtMinus = this._ctx.measureText("-").width
         if(this.showxgrad) {
             if(this.logscalex) {
-                for(let xpow = -this.maxgradx; xpow <= this.maxgradx; xpow+=1) {
-                    textWidth = this._ctx.measureText("10"+textsup(xpow)).width
+                for(let xpow = -this.maxgradx; xpow <= this.maxgradx; xpow += 1) {
+                    textWidth = this._ctx.measureText("10" + textsup(xpow)).width
                     if(xpow !== 0)
-                        this.drawVisibleText("10"+textsup(xpow), this.x2px(Math.pow(10,xpow))-textWidth/2, axisxpx+16+(6*(xpow===1)))
+                        this.drawVisibleText("10" + textsup(xpow), this.x2px(Math.pow(10, xpow)) - textWidth / 2, axisxpx + 16 + (6 * (xpow === 1)))
                 }
             } else {
                 for(let x = 1; x < this.axesSteps.x.maxDraw; x += 1) {
-                    let drawX = x*this.axesSteps.x.value
-                    let txtX = this.axesSteps.x.expression.simplify(x).toString().replace(/^\((.+)\)$/, '$1')
+                    let drawX = x * this.axesSteps.x.value
+                    let txtX = this.axesSteps.x.expression.simplify(x).toString().replace(/^\((.+)\)$/, "$1")
                     let textHeight = this.measureText(txtX).height
-                    this.drawVisibleText(txtX, this.x2px(drawX)-4, axisxpx+this.textsize/2+textHeight)
-                    this.drawVisibleText('-'+txtX, this.x2px(-drawX)-4, axisxpx+this.textsize/2+textHeight)
+                    this.drawVisibleText(txtX, this.x2px(drawX) - 4, axisxpx + this.textsize / 2 + textHeight)
+                    this.drawVisibleText("-" + txtX, this.x2px(-drawX) - 4, axisxpx + this.textsize / 2 + textHeight)
                 }
             }
         }
         if(this.showygrad) {
             for(let y = 0; y < this.axesSteps.y.maxDraw; y += 1) {
-                let drawY = y*this.axesSteps.y.value
-                let txtY = this.axesSteps.y.expression.simplify(y).toString().replace(/^\((.+)\)$/, '$1')
+                let drawY = y * this.axesSteps.y.value
+                let txtY = this.axesSteps.y.expression.simplify(y).toString().replace(/^\((.+)\)$/, "$1")
                 textWidth = this._ctx.measureText(txtY).width
-                this.drawVisibleText(txtY, axisypx-6-textWidth, this.y2px(drawY)+4+(10*(y===0)))
+                this.drawVisibleText(txtY, axisypx - 6 - textWidth, this.y2px(drawY) + 4 + (10 * (y === 0)))
                 if(y !== 0)
-                    this.drawVisibleText('-'+txtY, axisypx-6-textWidth-txtMinus, this.y2px(-drawY)+4)
+                    this.drawVisibleText("-" + txtY, axisypx - 6 - textWidth - txtMinus, this.y2px(-drawY) + 4)
             }
         }
         this._ctx.fillStyle = "#FFFFFF"
@@ -348,7 +394,7 @@ class CanvasAPI extends Module {
     drawVisibleText(text, x, y) {
         if(x > 0 && x < this.width && y > 0 && y < this.height) {
             text.toString().split("\n").forEach((txt, i) => {
-                this._ctx.fillText(txt, x, y+(this.textsize*i))
+                this._ctx.fillText(txt, x, y + (this.textsize * i))
             })
         }
     }
@@ -363,7 +409,7 @@ class CanvasAPI extends Module {
      * @param {number} height
      */
     drawVisibleImage(image, x, y, width, height) {
-        this._canvas.markDirty(Qt.rect(x, y, width, height));
+        this._canvas.markDirty(Qt.rect(x, y, width, height))
         this._ctx.drawImage(image, x, y, width, height)
     }
 
@@ -380,7 +426,7 @@ class CanvasAPI extends Module {
             theight += defaultHeight
             if(this._ctx.measureText(txt).width > twidth) twidth = this._ctx.measureText(txt).width
         }
-        return {'width': twidth, 'height': theight}
+        return { "width": twidth, "height": theight }
     }
 
     /**
@@ -392,9 +438,9 @@ class CanvasAPI extends Module {
     x2px(x) {
         if(this.logscalex) {
             const logxmin = Math.log(this.xmin)
-            return (Math.log(x)-logxmin)*this.xzoom
+            return (Math.log(x) - logxmin) * this.xzoom
         } else
-            return (x - this.xmin)*this.xzoom
+            return (x - this.xmin) * this.xzoom
     }
 
     /**
@@ -415,9 +461,9 @@ class CanvasAPI extends Module {
      */
     px2x(px) {
         if(this.logscalex) {
-            return Math.exp(px/this.xzoom+Math.log(this.xmin))
+            return Math.exp(px / this.xzoom + Math.log(this.xmin))
         } else
-            return (px/this.xzoom+this.xmin)
+            return (px / this.xzoom + this.xmin)
     }
 
     /**
@@ -427,7 +473,7 @@ class CanvasAPI extends Module {
      * @returns {number}
      */
     px2y(px) {
-        return -(px/this.yzoom-this.ymax)
+        return -(px / this.yzoom - this.ymax)
     }
 
     /**
@@ -448,10 +494,10 @@ class CanvasAPI extends Module {
      * @param {number} y2
      */
     drawLine(x1, y1, x2, y2) {
-        this._ctx.beginPath();
-        this._ctx.moveTo(x1, y1);
-        this._ctx.lineTo(x2, y2);
-        this._ctx.stroke();
+        this._ctx.beginPath()
+        this._ctx.moveTo(x1, y1)
+        this._ctx.lineTo(x2, y2)
+        this._ctx.stroke()
     }
 
     /**
@@ -463,9 +509,9 @@ class CanvasAPI extends Module {
      * @param {number} dashPxSize
      */
     drawDashedLine(x1, y1, x2, y2, dashPxSize = 6) {
-        this._ctx.setLineDash([dashPxSize/2, dashPxSize]);
+        this._ctx.setLineDash([dashPxSize / 2, dashPxSize])
         this.drawLine(x1, y1, x2, y2)
-        this._ctx.setLineDash([]);
+        this._ctx.setLineDash([])
     }
 
     /**
@@ -476,7 +522,7 @@ class CanvasAPI extends Module {
      */
     renderLatexImage(ltxText, color, callback) {
         const onRendered = (imgData) => {
-            if(!this._canvas.isImageLoaded(imgData.source) && !this._canvas.isImageLoading(imgData.source)){
+            if(!this._canvas.isImageLoaded(imgData.source) && !this._canvas.isImageLoading(imgData.source)) {
                 // Wait until the image is loaded to callback.
                 this._canvas.loadImage(imgData.source)
                 this._canvas.imageLoaders[imgData.source] = [callback, imgData]
@@ -496,8 +542,13 @@ class CanvasAPI extends Module {
     // Context methods
     //
 
-    get font() { return this._ctx.font }
-    set font(value) { return this._ctx.font = value }
+    get font() {
+        return this._ctx.font
+    }
+
+    set font(value) {
+        return this._ctx.font = value
+    }
 
     /**
      * Draws an act on the canvas centered on a point.
@@ -508,7 +559,7 @@ class CanvasAPI extends Module {
      * @param {number} endAngle
      * @param {boolean} counterclockwise
      */
-    arc(x, y, radius, startAngle, endAngle, counterclockwise=false) {
+    arc(x, y, radius, startAngle, endAngle, counterclockwise = false) {
         this._ctx.beginPath()
         this._ctx.arc(x, y, radius, startAngle, endAngle, counterclockwise)
         this._ctx.stroke()
@@ -521,9 +572,9 @@ class CanvasAPI extends Module {
      * @param {number} radius
      */
     disc(x, y, radius) {
-        this._ctx.beginPath();
+        this._ctx.beginPath()
         this._ctx.arc(x, y, radius, 0, 2 * Math.PI)
-        this._ctx.fill();
+        this._ctx.fill()
     }
 
     /**
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/common.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/common.mjs
index 1b68b89..6902745 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/common.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/common.mjs
@@ -16,6 +16,8 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+import { Interface } from "./interface.mjs"
+
 /**
  * Base class for global APIs in runtime.
  */
@@ -24,22 +26,30 @@ export class Module {
     /**
      *
      * @param {string} name - Name of the API
-     * @param {(Module|undefined)[]} requires - List of APIs required to initialize this one.
+     * @param {Object.<string, (Interface|string)>} initializationParameters - List of parameters for the initialize function.
      */
-    constructor(name, requires = []) {
+    constructor(name, initializationParameters = {}) {
         console.log(`Loading module ${name}...`)
-        this.__check_requirements(requires, name)
+        this.__name = name
+        this.__initializationParameters = initializationParameters
+        this.initialized = false
     }
 
     /**
      * Checks if all requirements are defined.
-     * @param {(Module|undefined)[]} requires
-     * @param {string} name
+     * @param {Object.<string, any>} options
      */
-    __check_requirements(requires, name) {
-        for(let requirement of requires) {
-            if(requirement === undefined)
-                throw new Error(`Requirement ${requires.indexOf(requirement)} of ${name} has not been initialized.`)
+    initialize(options) {
+        if(this.initialized)
+            throw new Error(`Cannot reinitialize module ${this.__name}.`)
+        for(const [name, value] of Object.entries(this.__initializationParameters)) {
+            if(!options.hasOwnProperty(name))
+                throw new Error(`Option '${name}' of initialize of module ${this.__name} does not exist.`)
+            if(typeof value === "function" && value.prototype instanceof Interface)
+                Interface.check_implementation(value, options[name])
+            else if(typeof value !== typeof options[name])
+                throw new Error(`Option '${name}' of initialize of module ${this.__name} is not a '${value}' (${typeof options[name]}).`)
         }
+        this.initialized = true
     }
 }
\ No newline at end of file
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/expreval.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/expreval.mjs
index 5ac849e..cc61434 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/expreval.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/expreval.mjs
@@ -36,10 +36,7 @@ const evalVariables = {
 
 export class ExprParserAPI extends Module {
     constructor() {
-        super("ExprParser", [
-            /** @type {ObjectsAPI} */
-            Modules.Objects
-        ])
+        super("ExprParser")
         this.currentVars = {}
         this._parser = new Parser()
 
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/history.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/history.mjs
index 27eedcb..09b45d6 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/history.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/history.mjs
@@ -18,29 +18,65 @@
 
 import { Module } from "./common.mjs"
 import Latex from "./latex.mjs"
+import { HistoryInterface, NUMBER, STRING } from "./interface.mjs"
 
 
 class HistoryAPI extends Module {
     constructor() {
-        super('History', [
-            Modules.Latex
-        ])
+        super("History", {
+            historyObj: HistoryInterface,
+            themeTextColor: STRING,
+            imageDepth: NUMBER,
+            fontSize: NUMBER
+        })
         // History QML object
-        this.history = null;
-        this.themeTextColor = "#ff0000";
-        this.imageDepth = 2;
-        this.fontSize = 14;
+        this.history = null
+        this.themeTextColor = "#FF0000"
+        this.imageDepth = 2
+        this.fontSize = 28
     }
 
-    undo() { this.history.undo() }
-    redo() { this.history.redo() }
-    clear() { this.history.clear() }
-    addToHistory(action) { this.history.addToHistory(action) }
-    unserialize(...data) { this.history.unserialize(...data) }
-    serialize() { return this.history.serialize() }
+    initialize({ historyObj, themeTextColor, imageDepth, fontSize }) {
+        super.initialize({ historyObj, themeTextColor, imageDepth, fontSize })
+        console.log("Initializing history...")
+        this.history = historyObj
+        this.themeTextColor = themeTextColor
+        this.imageDepth = imageDepth
+        this.fontSize = fontSize
+    }
+
+    undo() {
+        if(!this.initialized) throw new Error("Attempting undo before initialize!")
+        this.history.undo()
+    }
+
+    redo() {
+        if(!this.initialized) throw new Error("Attempting redo before initialize!")
+        this.history.redo()
+    }
+
+    clear() {
+        if(!this.initialized) throw new Error("Attempting clear before initialize!")
+        this.history.clear()
+    }
+
+    addToHistory(action) {
+        if(!this.initialized) throw new Error("Attempting addToHistory before initialize!")
+        this.history.addToHistory(action)
+    }
+
+    unserialize(...data) {
+        if(!this.initialized) throw new Error("Attempting unserialize before initialize!")
+        this.history.unserialize(...data)
+    }
+
+    serialize() {
+        if(!this.initialized) throw new Error("Attempting serialize before initialize!")
+        return this.history.serialize()
+    }
 }
 
 /** @type {HistoryAPI} */
 Modules.History = Modules.History || new HistoryAPI()
 
-export default Modules.History
\ No newline at end of file
+export default Modules.History
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/interface.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/interface.mjs
new file mode 100644
index 0000000..9da3f4d
--- /dev/null
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/interface.mjs
@@ -0,0 +1,130 @@
+/**
+ *  LogarithmPlotter - 2D plotter software to make BODE plots, sequences and distribution functions.
+ *  Copyright (C) 2021-2024  Ad5001
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+export const NUMBER = 0
+export const STRING = "string"
+export const BOOLEAN = true
+export const OBJECT = {}
+export const FUNCTION = () => {
+}
+
+
+export class Interface {
+    /**
+     * Checks if the class to check implements the given interface.
+     * Throws an error if the implementation does not conform to the interface.
+     * @param {typeof Interface} interface_
+     * @param {object} classToCheck
+     * @return {boolean}
+     */
+    static check_implementation(interface_, classToCheck) {
+        const properties = new interface_()
+        const interfaceName = interface_.name
+        const toCheckName = classToCheck.constructor.name
+        for(const [property, value] of Object.entries(properties))
+            if(property !== "implement") {
+                console.log(classToCheck[property], value)
+                if(!classToCheck.hasOwnProperty(property))
+                    // Check if the property exist
+                    throw new Error(`Property '${property}' (${typeof value}) is present in interface ${interfaceName}, but not in implementation ${toCheckName}.`)
+                else if((typeof value) !== (typeof classToCheck[property]))
+                    // Compare the types
+                    throw new Error(`Property '${property}' of ${interfaceName} implementation ${toCheckName} is a '${typeof classToCheck[property]}' and not a '${typeof value}'.`)
+                else if((typeof value) === "object")
+                    // Test type of object.
+                    if(value instanceof Interface)
+                        Interface.check_implementation(value, classToCheck[property])
+                    else if(value.prototype && !(classToCheck[property] instanceof value))
+                        throw new Error(`Property '${property}' of ${interfaceName} implementation ${toCheckName} is not '${value.constructor.name}'.`)
+            }
+    }
+
+    /**
+     * Decorator to automatically check if a class conforms to the current interface.
+     * @param {object} class_
+     */
+    implement(class_) {
+        Interface.check_implementation(this, class_)
+        return class_
+    }
+}
+
+
+export class SettingsInterface extends Interface {
+    constructor() {
+        super()
+        this.width = NUMBER
+        this.height = NUMBER
+        this.xmin = NUMBER
+        this.ymax = NUMBER
+        this.xzoom = NUMBER
+        this.yzoom = NUMBER
+        this.xaxisstep = STRING
+        this.yaxisstep = STRING
+        this.xlabel = STRING
+        this.ylabel = STRING
+        this.linewidth = NUMBER
+        this.textsize = NUMBER
+        this.logscalex = BOOLEAN
+        this.showxgrad = BOOLEAN
+        this.showygrad = BOOLEAN
+    }
+}
+
+export class CanvasInterface extends SettingsInterface {
+    constructor() {
+        super()
+        this.imageLoaders = OBJECT
+        /** @type {function(string): CanvasRenderingContext2D} */
+        this.getContext = FUNCTION
+        /** @type {function(rect)} */
+        this.markDirty = FUNCTION
+        /** @type {function(string)} */
+        this.loadImage = FUNCTION
+        /** @type {function()} */
+        this.requestPaint = FUNCTION
+    }
+}
+
+export class RootInterface extends Interface {
+    constructor() {
+        super()
+        this.width = NUMBER
+        this.height = NUMBER
+        this.updateObjectsLists = FUNCTION
+    }
+}
+
+export class DialogInterface extends Interface {
+    constructor() {
+        super()
+        this.show = FUNCTION
+    }
+}
+
+export class HistoryInterface extends Interface {
+    constructor() {
+        super()
+        this.undo = FUNCTION
+        this.redo = FUNCTION
+        this.clear = FUNCTION
+        this.addToHistory = FUNCTION
+        this.unserialize = FUNCTION
+        this.serialize = FUNCTION
+    }
+}
\ No newline at end of file
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/io.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/io.mjs
index bc9a1db..2a540a7 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/io.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/io.mjs
@@ -20,14 +20,17 @@ import { Module } from "./common.mjs"
 import Objects from "./objects.mjs"
 import History from "./history.mjs"
 import Canvas from "./canvas.mjs"
+import { DialogInterface, FUNCTION, Interface, RootInterface, SettingsInterface } from "./interface.mjs"
+
 
 class IOAPI extends Module {
 
     constructor() {
-        super("IO", [
-            Modules.Objects,
-            Modules.History
-        ])
+        super("IO", {
+            alert: DialogInterface,
+            root: RootInterface,
+            settings: SettingsInterface
+        })
         /**
          * Path of the currently opened file. Empty if no file is opened.
          * @type {string}
@@ -37,12 +40,13 @@ class IOAPI extends Module {
 
     /**
      * Initializes module with QML elements.
-     * @param {{width: number, height: number, updateObjectsLists: function()}} rootElement
-     * @param {Settings} settings
+     * @param {RootInterface} root
+     * @param {SettingsInterface} settings
      * @param {{show: function(string)}} alert
      */
-    initialize(rootElement, settings, alert) {
-        this.rootElement = rootElement
+    initialize({ root, settings, alert }) {
+        super.initialize({ root, settings, alert })
+        this.rootElement = root
         this.settings = settings
         this.alert = alert
     }
@@ -52,6 +56,7 @@ class IOAPI extends Module {
      * @param {string} filename
      */
     saveDiagram(filename) {
+        if(!this.initialized) throw new Error("Attempting saveDiagram before initialize!")
         // Add extension if necessary
         if(["lpf"].indexOf(filename.split(".")[filename.split(".").length - 1]) === -1)
             filename += ".lpf"
@@ -93,11 +98,13 @@ class IOAPI extends Module {
      * @param {string} filename
      */
     loadDiagram(filename) {
+        if(!this.initialized) throw new Error("Attempting loadDiagram before initialize!")
+        if(!History.initialized) throw new Error("Attempting loadDiagram before history is initialized!")
         let basename = filename.split("/").pop()
         this.alert.show(qsTranslate("io", "Loading file '%1'.").arg(basename))
         let data = JSON.parse(Helper.load(filename))
         let error = ""
-        if(Object.keys(data).includes("type") && data["type"] === "logplotv1") {
+        if(data.hasOwnProperty("type") && data["type"] === "logplotv1") {
             History.clear()
             // Importing settings
             this.settings.saveFilename = filename
@@ -129,7 +136,7 @@ class IOAPI extends Module {
                 // Another way would be to change the reference as well, but I feel like the code would be less clean.
             }
             for(let objType in data["objects"]) {
-                if(Object.keys(Objects.types).indexOf(objType) > -1) {
+                if(Object.keys(Objects.types).includes(objType)) {
                     Objects.currentObjects[objType] = []
                     for(let objData of data["objects"][objType]) {
                         /** @type {DrawableObject} */
@@ -157,7 +164,7 @@ class IOAPI extends Module {
         }
         if(error !== "") {
             console.log(error)
-            this.alert.show(qsTranslate("io", "Could not save file: ") + error)
+            this.alert.show(qsTranslate("io", "Could not load file: ") + error)
             // TODO: Error handling
             return
         }
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/latex.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/latex.mjs
index 32f048b..f2e9b0b 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/latex.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/latex.mjs
@@ -58,10 +58,7 @@ class LatexRenderResult {
 
 class LatexAPI extends Module {
     constructor() {
-        super("Latex", [
-            /** @type {ExprParserAPI} */
-            Modules.ExprParser
-        ])
+        super("Latex")
         /**
          * true if latex has been enabled by the user, false otherwise.
          */
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/preferences.mjs b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/preferences.mjs
index e76596e..389a5ba 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/preferences.mjs
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/module/preferences.mjs
@@ -22,10 +22,7 @@ import DefaultGraph from "../preferences/default.mjs"
 
 class PreferencesAPI extends Module {
     constructor() {
-        super('Preferences', [
-            Modules.Canvas,
-            Modules.Latex
-        ])
+        super('Preferences')
 
         this.categories = {
             [QT_TRANSLATE_NOOP('settingCategory', 'general')]: General,