<snapdata remixID="8924744"><project name="U2L4-checkerboard_SV" app="Snap! 5.1, http://snap.berkeley.edu" version="1"><notes></notes><thumbnail>data:image/png;base64,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</thumbnail><stage name="Stage" width="480" height="360" costume="0" color="255,255,255,1" tempo="60" threadsafe="false" volume="100" pan="0" lines="flat" ternary="true" codify="false" inheritance="false" sublistIDs="false" scheduled="false" id="1"><pentrails>data:image/png;base64,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</pentrails><costumes><list struct="atomic" id="2"></list></costumes><sounds><list struct="atomic" id="3"></list></sounds><variables></variables><blocks></blocks><scripts></scripts><sprites><sprite name="Sprite" idx="1" x="160.25553662691658" y="155.05110732538333" heading="90" scale="1" volume="100" pan="0" rotation="1" draggable="true" costume="0" color="8,5,0,1" pen="tip" id="8"><costumes><list struct="atomic" id="9"></list></costumes><sounds><list struct="atomic" id="10"></list></sounds><blocks></blocks><variables></variables><scripts><script x="16" y="22"><block s="receiveGo"></block><custom-block s="create a checkerboard"></custom-block></script></scripts></sprite></sprites></stage><hidden></hidden><headers></headers><code></code><blocks><block-definition s="set flag %&apos;which&apos; to %&apos;tf&apos;" type="command" category="sensing"><header></header><code></code><translations></translations><inputs><input type="%s" readonly="true"><options>Presentation mode&#xD;Retina display support&#xD;Long form input dialog&#xD;Plain prototype labels&#xD;Input sliders&#xD;Execute on slider change&#xD;Clicking sound&#xD;Turbo mode&#xD;Flat design&#xD;Keyboard editing&#xD;Table support&#xD;Table lines&#xD;Visible stepping&#xD;Thread safe scripts&#xD;Prefer smooth animations&#xD;Flat line ends&#xD;Codification support&#xD;Inheritance support</options></input><input type="%b"></input></inputs><script><block s="doRun"><block s="reportJSFunction"><list><l>which</l><l>tf</l></list><l>var   stage = this.parentThatIsA(StageMorph),&#xD;        ide = stage.parentThatIsA(IDE_Morph),&#xD;        world = stage.parentThatIsA(WorldMorph);&#xD;&#xD;if (tf != !!tf) return;&#xD;&#xD;try{&#xD;ide.savingPreferences = false;&#xD;&#xD;switch (which) {&#xD;    case &apos;Presentation mode&apos;:&#xD;        if (tf != ide.isAppMode) ide.toggleAppMode();&#xD;        break;&#xD;    case &apos;Retina display support&apos;:&#xD;        if (tf != isRetinaEnabled()) ide.toggleRetina();&#xD;        break;&#xD;    case &apos;Long form input dialog&apos;:&#xD;        if (tf != InputSlotDialogMorph.prototype.isLaunchingExpanded)&#xD;            ide.toggleLongFormInputDialog();&#xD;        break;&#xD;    case &apos;Plain prototype labels&apos;:&#xD;        if (tf != BlockLabelPlaceHolderMorph.prototype.plainLabel)&#xD;            ide.togglePlainPrototypeLabels();&#xD;        break;&#xD;    case &apos;Input sliders&apos;:&#xD;        MorphicPreferences.useSliderForInput = tf;&#xD;        break;&#xD;    case &apos;Execute on slider change&apos;:&#xD;        ArgMorph.prototype.executeOnSliderEdit = tf;&#xD;        break;&#xD;    case &apos;Clicking sound&apos;:&#xD;        if (tf != !!BlockMorph.prototype.snapSound)&#xD;            BlockMorph.prototype.toggleSnapSound();&#xD;        break;&#xD;    case &apos;Turbo mode&apos;:&#xD;        if (tf != stage.isFastTracked)&#xD;            ide.toggleFastTracking();&#xD;        break;&#xD;    case &apos;Flat design&apos;:&#xD;        if (tf == MorphicPreferences.isFlat) break;&#xD;        if (tf)&#xD;            ide.flatDesign();&#xD;        else&#xD;            ide.defaultDesign();&#xD;        break;&#xD;    case &apos;Keyboard editing&apos;:&#xD;            ScriptsMorph.prototype.enableKeyboard = tf;&#xD;        break;&#xD;    case &apos;Table support&apos;:&#xD;            List.prototype.enableTables = tf;&#xD;        break;&#xD;    case &apos;Table lines&apos;:&#xD;                TableMorph.prototype.highContrast = tf;&#xD;        break;&#xD;    case &apos;Visible stepping&apos;:&#xD;        if (tf != Process.prototype.enableSingleStepping)&#xD;            ide.toggleSingleStepping();&#xD;        break;&#xD;    case &apos;Thread safe scripts&apos;:&#xD;        stage.isThreadSafe = tf;&#xD;        break;&#xD;    case &apos;Prefer smooth animations&apos;:&#xD;        if (tf != (StageMorph.prototype.frameRate &gt; 0))&#xD;            ide.toggleVariableFrameRate();&#xD;        break;&#xD;    case &apos;Flat line 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