Strange behavior when extending a window

The window moves downward when tying to extend its size by pulling the window's top edge. This happens in the following conditions.

Conditions :

• The window's minimum size and screen's resolution size are the same
• The window's geometry size is same or bigger than the screen resolution

How to reproduce
Set the screen's resolution to 1920 * 1080 and use QtBug94361.zip

or
1. Use QtBug94361.zip
2. Change minimum size to the screen's resolution size
3. Change geometry's size to something bigger than #2

Run the application and, grab and pull the window's top edge to extend the window.

Result :
The window starts to move downward direction