Bug 120920 – Element [draggable=true] does not start dragging when window in background

• Component: UI Events
• Status: UNCONFIRMED

Steps to reproduce the problem:
1. Open attached HTML file.
2. Switch to another any window (eg. open Notepad or Calc)
3. Press left mouse button on red square in the background (not focused) window, hold during 100ms (or more), then start moving your mouse.

What is the expected behavior?
Red square get dragged (HTML5 drag'n'drop).

What went wrong?
Red square is not draggable.

Did this work before? N/A 

OS Version: 6.1 (Windows 7, Windows Server 2008 R2)

This bugs occurs only when "draggable" attribute is set by setTimeout (with timeout > 10ms).
If window, you switched from, has feature "Always stay on Top", the bug does not happen.
This is Windows OS only related.

I'm working on implemementing text Drag'n'Drop (native) feature in web-based code editor (http://ace.ajax.org/). It has feature "drag delay" (Mac users should know this feature), that's why I need to set [draggable] in setTimeout.

Can anyone give me any clue why this behavior relays on timeout for setTimeout and "Always stay on Top" feature of a second window?

Created attachment 210837 [details]
Test Case

This bug is not reproducible when you switch from such windows as Task Manager, Screen Keyboard, or when you focused on Desktop.

I tested this on Linux. It seems to work fine. I did not test it on Mac, but I guess it would work fine too.
So this is Windows only bug (tested on Windows7)

[Zan Dobersek]

Are you using Chromium?