Challenge: Find the use of rectangles

InitMenuHandler

signed int __thiscall InitMenuHandler(tag_message *msg)
{
  signed int result; // eax@26
  int v2; // ST48_4@29
  int v3; // [sp+Ch] [bp-24h]@27
  signed int v5; // [sp+1Ch] [bp-14h]@40
  signed int v6; // [sp+20h] [bp-10h]@4
  signed int v7; // [sp+24h] [bp-Ch]@1
  int highID; // [sp+2Ch] [bp-4h]@32
  signed int highIDa; // [sp+2Ch] [bp-4h]@40

  v7 = 0;
  PollSound();
  if ( BYTE1(msg->inputTypeBitmask) & 2 )
  {
    if ( msg->xCoordOrKeycode == 12 || msg->xCoordOrKeycode == 14 )
    {
      v6 = -1;
      switch ( msg->yCoordOrFieldID )
      {
        case 101:
          v6 = 0;                               // new game
          break;
        case 102:
          v6 = 1;                               // load game
          break;
        case 103:                               // high scores
          v6 = 2;
          break;
        case 104:                               // credits
          v6 = 3;
          break;
        case 105:                               // quit
          v6 = 4;
          break;
        default:
          break;
      }
      if ( v6 >= 0 )
        NormalDialog(gEventText[v6 + 116], 4, -1, -1, -1, 0, -1, 0, -1, 0);
    }
  }
  else
  {
    switch ( msg->eventCode )
    {
      case INPUT_KEYDOWN_EVENT_CODE:
        switch ( msg->xCoordOrKeycode )
        {
          case '1':
            gpWindowManager->buttonPressedCode = 101;
            v7 = 1;
            break;
          case '&':
            gpWindowManager->buttonPressedCode = 102;
            v7 = 1;
            break;
          case '.':
            gpWindowManager->buttonPressedCode = 104;
            v7 = 1;
            break;
          case '#':
            gpWindowManager->buttonPressedCode = 103;
            v7 = 1;
            break;
          case '\x10':
            gpWindowManager->buttonPressedCode = 105;
            v7 = 1;
            break;
          default:
            goto LABEL_54;
        }
        break;
      case INPUT_GUI_MESSAGE_CODE:
        if ( msg->yCoordOrFieldID < 101 || msg->yCoordOrFieldID > 107 )
          return 0;
        v3 = msg->xCoordOrKeycode;
        if ( v3 == 12 )
        {
          if ( msg->yCoordOrFieldID != 107 )
          {
            v2 = msg->yCoordOrFieldID - 101;
            msg->eventCode = 512;
            msg->yCoordOrFieldID = v2 + 11;
            msg->xCoordOrKeycode = 4;
            msg->payload = (void *)(4 * v2 + 3);
            heroWindow::BroadcastMessage(gpInitWin, msg);
            heroWindow::DrawWindow(gpInitWin, 0, v2 + 11, v2 + 11);
            heroWindowManager::UpdateScreenRegion(
              gpWindowManager,
              (unsigned __int16)IMHotSpots[4 * v2],
              (unsigned __int16)word_50CFEA[4 * v2],
              (unsigned __int16)word_50CFEC[4 * v2],
              (unsigned __int16)word_50CFEE[4 * v2]);
          }
        }
        else if ( v3 == 13 )
        {
          if ( msg->yCoordOrFieldID == 107 )
          {
            PlaySmacker(38);
            resourceManager::GetBackdrop(gpResourceManager, "heroes.icn", gpWindowManager->screenBuffer, 1);
            heroWindow::DrawWindow(gpInitWin, 0);
            heroWindowManager::UpdateScreenRegion(gpWindowManager, 0, 0, 0x280u, 480);
            soundManager::PlayAmbientMusic(gpSoundManager, 42, 0, -1);
          }
          else
          {
            gpWindowManager->buttonPressedCode = msg->yCoordOrFieldID;
            for ( highID = 11; highID <= 15; ++highID )
            {
              msg->eventCode = 512;
              msg->yCoordOrFieldID = highID;
              msg->xCoordOrKeycode = 4;
              msg->payload = (void *)(4 * highID - 44);
              heroWindow::BroadcastMessage(gpInitWin, msg);
            }
            heroWindow::DrawWindow(gpInitWin, 0, 11, 15);
            heroWindowManager::UpdateScreenRegion(gpWindowManager, 0, 105, 0x235u, 375);
            v7 = 1;
          }
        }
        break;
      case INPUT_MOUSEMOVE_EVENT_CODE:
        v5 = -1;
        for ( highIDa = 0; highIDa < 5; ++highIDa )
        {
          if ( (unsigned __int16)IMHotSpots[4 * highIDa] <= msg->altXCoord
            && (unsigned __int16)word_50CFEA[4 * highIDa] <= msg->altYCoord
            && (unsigned __int16)IMHotSpots[4 * highIDa] + (unsigned __int16)word_50CFEC[4 * highIDa] > msg->altXCoord
            && (unsigned __int16)word_50CFEE[4 * highIDa] + (unsigned __int16)word_50CFEA[4 * highIDa] > msg->altYCoord )
            v5 = highIDa;
        }
        if ( v5 != lastIMHoverID )
        {
          if ( lastIMHoverID != -1 )
          {
            msg->eventCode = 512;
            msg->yCoordOrFieldID = lastIMHoverID + 11;
            msg->xCoordOrKeycode = 4;
            msg->payload = (void *)(4 * lastIMHoverID + 1);
            heroWindow::BroadcastMessage(gpInitWin, msg);
            heroWindow::DrawWindow(gpInitWin, 0, lastIMHoverID + 11, lastIMHoverID + 11);
            heroWindowManager::UpdateScreenRegion(
              gpWindowManager,
              (unsigned __int16)IMHotSpots[4 * lastIMHoverID],
              (unsigned __int16)word_50CFEA[4 * lastIMHoverID],
              (unsigned __int16)word_50CFEC[4 * lastIMHoverID],
              (unsigned __int16)word_50CFEE[4 * lastIMHoverID]);
          }
          if ( v5 != -1 )
          {
            msg->eventCode = 512;
            msg->yCoordOrFieldID = v5 + 11;
            msg->xCoordOrKeycode = 4;
            msg->payload = (void *)(4 * v5 + 2);
            heroWindow::BroadcastMessage(gpInitWin, msg);
            heroWindow::DrawWindow(gpInitWin, 0, v5 + 11, v5 + 11);
            heroWindowManager::UpdateScreenRegion(
              gpWindowManager,
              (unsigned __int16)IMHotSpots[4 * v5],
              (unsigned __int16)word_50CFEA[4 * v5],
              (unsigned __int16)word_50CFEC[4 * v5],
              (unsigned __int16)word_50CFEE[4 * v5]);
          }
          lastIMHoverID = v5;
        }
        break;
    }
  }
LABEL_54:
  if ( v7 || giMenuCommand != -1 )
  {
    msg->eventCode = 512;
    msg->yCoordOrFieldID = 10;
    msg->xCoordOrKeycode = msg->yCoordOrFieldID;
    result = 2;
  }
  else
  {
    CheckShingleUpdate();
    result = 1;
  }
  return result;
}