Scrolling shouldn't drop a duplicated block

Expected Behavior

Sometimes once you've duplicated a block, you need to scroll a pretty far distance before you get to where you want to place it. (This is especially frequent if you use Scratch on a small screen or are zoomed in to make the blocks bigger.) Duplicating a block attaches the block to the cursor, so that it follows your mouse even though you aren't dragging. This block should stay attached to your cursor until you click the place where you want to drop it.

Actual Behavior

If you scroll (via scrollwheel) while a block is attached to your cursor, that block will get "dropped", being placed onto the workspace wherever your mouse was when you started dragging. This is impractical because it means you have to click and drag your block back up to get it where you want it.

Steps to Reproduce

Duplicate a block so that it is attached to your cursor, then scroll the workspace via the scrollwheel (or a trackpad, etc).

Operating System and Browser

Firefox 65.0b7, Linux (Debian).

Reproduce the issue in the Scratch Blocks workspace by duplicating a block and scrolling with the mouse or trackpad. Trace the workspace scroll and block-drop handling; done means the duplicated block stays attached while scrolling and is placed only after clicking.