1714647 - Browser window should not move (or resize) if the only tab in a window is detached onto itself

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[Tracy Walker [:tracy]]

This bug has likely been around for a very long time. See bug 675401 for a specific condition that exposes this bug. However, the issue is more generally reproducible as follows:

STR:

1. Have the browser open with a single tab.
2. Ensure that browser window is not full screen or maximized. The issue does occur under those circumstances, (again see 675401). However, it is easier to see the undesired effect if the browser window is taking up less than maximum screen space.
3. Drag the browser window's only tab down into page content.

Tested results:
The appearance is that the window is moved. My guess is, behind the scenes, the mechanics of detaching a tab are implemented, creating a new window with the tab contents. And because the previous window no longer has any tabs, it is closed.

Expected results:
When dropping an only tab on itself, nothing should happen. No movement of, or creation of a window from the dragged tab. Just leave the existing window in place, as is.

Basically check on drag; is this the only tab in this browser window,? if yes, is it being dropped into itself? If yes, on drop, do nothing except release the drag state (thumbnail)