Source of https://draw.tsak.net/drawer.swf. This draws a painting app and then lets the user draw a painting and send the movements to the backend.

drawer.as

movie 'drawer.swf' {
// flash 6, total frames: 1, frame rate: 12 fps, 640x480 px, compressed

  frame 1 {
    function pushSave(action) {
      _root.picture.pic.push(action + '#');
    }

    colDist = 10;
    colWidth = 8;
    lineWidth = 1;
    actCol = 0;
    picture = new LoadVars();
    picture.pic = new Array();
    hex = new Array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F');
    _root.createEmptyMovieClip('drawingBoard', 1);
    with (drawingBoard) {
      lineStyle(1, 0, 100);
      moveTo(1, 1);
      lineTo(639, 1);
      lineTo(639, 479);
      lineTo(1, 479);
      lineTo(1, 1);
      moveTo(58, 1);
      lineTo(58, 479);
      c = 0;
      d = 1;
      i = 1;
      while (i <= 64) {
        if (i == 1) {
          this_col = '0x000000';
        } else {
          if (i == 2) {
            this_col = '0xFFFFFF';
          } else {
            this_col = '0x' + hex[Math.round(Math.random() * 15)] + hex[Math.round(Math.random() * 15)] + hex[Math.round(Math.random() * 15)] + hex[Math.round(Math.random() * 15)] + hex[Math.round(Math.random() * 15)] + hex[Math.round(Math.random() * 15)];
          }
        }
        ++c;
        ++e;
        createEmptyMovieClip('colsel' + i, e);
        this_colMC = eval('colsel' + i);
        with (this_colMC) {
          lineStyle(1, 0, 100);
          beginFill(this_col);
          moveTo(c * colDist, d * colDist);
          lineTo(c * colDist + colWidth, d * colDist);
          lineTo(c * colDist + colWidth, d * colDist + colWidth);
          lineTo(c * colDist, d * colDist + colWidth);
          lineTo(c * colDist, d * colDist);
          endFill();
        }
        this_colMC.col = this_col;
        this_colMC.onPress = function () {
          _root.drawingBoard.paper.lineStyle(_root.lineWidth, this.col);
          _root.actCol = this.col;
          _root.pushSave('s_' + _root.lineWidth + '_' + this.col);
        };

        if (c > 3) {
          c = 0;
          ++d;
        }
        ++i;
      }
      i = 1;
      while (i < 10) {
        createEmptyMovieClip('line' + i, i + e);
        this_linMC = eval('line' + i);
        with (this_linMC) {
          lineStyle(1, 0, 100);
          beginFill(16777215);
          moveTo(10, i * 20 + 202);
          lineTo(50, i * 20 + 202);
          lineTo(50, i * 20 + 218);
          lineTo(10, i * 20 + 218);
          lineTo(10, i * 20 + 202);
          endFill();
          lineStyle(i, 0, 100);
          moveTo(12 + i, i * 20 + 210);
          lineTo(48 - i, i * 20 + 210);
        }
        this_linMC.line = i;
        this_linMC.onPress = function () {
          _root.drawingBoard.paper.lineStyle(this.line, _root.actCol);
          _root.lineWidth = this.line;
          _root.pushSave('s_' + this.line + '_' + _root.actCol);
        };

        ++i;
      }
      createEmptyMovieClip('saveButton', i + e + 3);
      with (saveButton) {
        lineStyle(1, 0, 100);
        beginFill(16777215);
        moveTo(10, 460);
        lineTo(50, 460);
        lineTo(50, 470);
        lineTo(10, 470);
        lineTo(10, 460);
        endFill();
        createTextField('mytext', 1, 10, 456, 40, 20);
        with (mytext) {
          multiline = false;
          wordWrap = false;
          border = false;
          selectable = false;
          text = 'save';
        }
        myformat = new TextFormat();
        with (myformat) {
          color = 0;
          bullet = false;
          bold = true;
          underline = false;
          font = 'Arial';
          size = 11;
          align = 'center';
        }
        mytext.setTextFormat(myformat);
      }
      saveButton.onPress = function () {
        _root.picture.send(_root.host + 'index.php', '', 'POST');
      };

      createEmptyMovieClip('clearButton', i + e + 4);
      with (clearButton) {
        lineStyle(1, 0, 100);
        beginFill(16777215);
        moveTo(10, 440);
        lineTo(50, 440);
        lineTo(50, 450);
        lineTo(10, 450);
        lineTo(10, 440);
        endFill();
        createTextField('mytext', 1, 10, 436, 40, 20);
        with (mytext) {
          multiline = false;
          wordWrap = false;
          border = false;
          selectable = false;
          text = 'clear';
        }
        myformat = new TextFormat();
        with (myformat) {
          color = 0;
          bullet = false;
          bold = true;
          underline = false;
          font = 'Arial';
          size = 11;
          align = 'center';
        }
        mytext.setTextFormat(myformat);
      }
      clearButton.onPress = function () {
        getURL('index.php?mode=draw');
      };

      createEmptyMovieClip('paperMask', i + e + 2);
      with (paperMask) {
        lineStyle(1, 16777215, 0);
        beginFill(16711680);
        moveTo(59, 2);
        lineTo(639, 2);
        lineTo(639, 479);
        lineTo(59, 479);
        lineTo(59, 2);
      }
      createEmptyMovieClip('paper', i + e + 1);
      paper.lineStyle(1, 0, 100);
      _root.pushSave('s_1_0x000000');
      paper.setMask(paperMask);
    }
    myListener = new Object();
    myListener.onMouseDown = function () {
      _root.drawingBoard.paper.moveTo(_root.drawingBoard.paper._xmouse, _root.drawingBoard.paper._ymouse);
      _root.pushSave('m_' + _root.drawingBoard.paper._xmouse + '_' + _root.drawingBoard.paper._ymouse);
      _root.drawing = true;
    };

    myListener.onMouseMove = function () {
      if (_root.drawing) {
        _root.drawingBoard.paper.lineTo(_root.drawingBoard.paper._xmouse, _root.drawingBoard.paper._ymouse);
        _root.pushSave('l_' + _root.drawingBoard.paper._xmouse + '_' + _root.drawingBoard.paper._ymouse);
      }
    };

    myListener.onMouseUp = function () {
      _root.drawing = false;
    };

    Mouse.addListener(myListener);
  }
}