Trash hotspot wrong when trash is full.

[NeilFraser]

1. Open this page:
   https://beta-dot-blockly-games.appspot.com/music
2. Drag a block over the trash. Explore the top/bottom/left/right boundaries of the hotspot. They are correct.
3. Drop the block into the trash.
4. Open the trash flyout, and drag the block out.
5. Drag this block over the trash. Explore the top/bottom/left/right boundaries of the hotspot. They are incorrect.

Affects both RTL and LTR.

[NeilFraser]

@BeksOmega I think this is yours?

[BeksOmega]

So digging into it I found that this is caused by the workspace calling recordDeleteAreas() when the trashcan lid is opened (i.e. when you click and it opens the flyout). This causes the trashcan to return the incorrect getClientRect() value, which changes the position of the hotspot.

This recordDeleteAreas call is being triggered by this line of code inside flyout.reflowInternal_(), because sometimes when a flyout reflows (i.e. zooms) the trashcan has to move. The thing is that the trashcan moving is bad behavior anyway, because it results in chasing, and was already fixed for bottom-anchored toolboxes.

So to fix this issue I'd like to anchor the trashcan & zoom controls to the start in end-anchored toolbox layouts and then remove the targetWorkspace_.resize() call.

[rachel-fenichel]

I agree, the root behaviour is bad, and fixing it would be better than adding in more special cases to mitigate it. So go for it.

[NeilFraser]

Fix confirmed. Thanks!