<snapdata remixID="8927241"><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="-120" y="-130" heading="90" scale="1" volume="100" pan="0" rotation="1" draggable="true" costume="0" color="255,47,31,1" 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="23" y="10"><block s="clear"></block><block s="gotoXY"><l>-120</l><l>110</l></block><custom-block s="checkerboard"></custom-block></script><script x="24" y="94.99999999999994"><custom-block s="draw red square size %n"><l></l></custom-block></script><script x="25" y="147.99999999999994"><custom-block s="draw black square size %n"><l></l></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 ends&apos;:&#xD;        SpriteMorph.prototype.useFlatLineEnds = tf;&#xD;        break;&#xD;    case &apos;Codification support&apos;:&#xD;        if (tf != StageMorph.prototype.enableCodeMapping) {&#xD;            StageMorph.prototype.enableCodeMapping = tf;&#xD;            ide.currentSprite.blocksCache.variables = null;&#xD;            ide.currentSprite.paletteCache.variables = null;&#xD;            ide.refreshPalette();&#xD;        }&#xD;        break;&#xD;    case &apos;Inheritance support&apos;:&#xD;        if (tf != StageMorph.prototype.enableInheritance) {&#xD;            StageMorph.prototype.enableInheritance = tf;&#xD;            ide.currentSprite.blocksCache.variables = null;&#xD;            ide.currentSprite.paletteCache.variables = null;&#xD;            ide.refreshPalette();&#xD;        }&#xD;        break;&#xD;};&#xD;}&#xD;finally {&#xD;ide.savingPreferences = false;&#xD;};&#xD;</l></block><list><block var="which"/><block var="tf"/></list></block></script></block-definition><block-definition s="draw brick, length: %&apos;length&apos; width: %&apos;width&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input><input type="%n"></input></inputs><script><block s="setColor"><color>145,26,68,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="width"/></block><block s="down"></block><block s="forward"><block var="length"/></block><block s="up"></block></script></block-definition><block-definition s="set flat line ends to %&apos;flag&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%b"></input></inputs><script><custom-block s="set flag %s to %b"><l>Flat line ends</l><block var="flag"/></custom-block></script></block-definition><block-definition s="draw black square size %&apos;size&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input></inputs><script><block s="setColor"><color>8,5,0,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="size"/></block><block s="down"></block><block s="forward"><block var="size"/></block><block s="up"></block></script></block-definition><block-definition s="draw red square size %&apos;size&apos;" type="command" category="pen"><header></header><code></code><translations></translations><inputs><input type="%n"></input></inputs><script><block s="setColor"><color>255,47,31,1</color></block><custom-block s="set flat line ends to %b"><block s="reportBoolean"><l><bool>true</bool></l></block></custom-block><block s="setSize"><block var="size"/></block><block s="down"></block><block s="forward"><block var="size"/></block><block s="up"></block></script></block-definition><block-definition s="checkerboard" type="command" category="pen"><header></header><code></code><translations></translations><inputs></inputs><script><block s="doRepeat"><l>4</l><script><block s="doRepeat"><l>4</l><script><custom-block s="draw red square size %n"><l>30</l></custom-block><custom-block s="draw black square size %n"><l>30</l></custom-block></script></block><block s="changeXPosition"><l>-240</l></block><block s="changeYPosition"><l>-30</l></block><block s="doRepeat"><l>4</l><script><custom-block s="draw black square size %n"><l>30</l></custom-block><custom-block s="draw red square size %n"><l>30</l></custom-block></script></block><block s="changeXPosition"><l>-240</l></block><block s="changeYPosition"><l>-30</l></block></script></block></script></block-definition></blocks><variables></variables></project><media name="U2L4-checkerboard_SV" app="Snap! 5.1, http://snap.berkeley.edu" version="1"></media></snapdata>