Steps to reproduce:

1. Create empty project.
2. Create new particle system (shuriken)
3. Select particle system.
4. In the inspector window, at right top corner press Open Editor.
5. Try to move the opened window to the sides, top, bottom.
6. Then maximize the window and try to minimise again to the normal size.

Expected result: All works the same as with normal window.
Actual result: Moving up and down or to the sides, moves the window not according to the mouse movement. Also, after maximizing, it is not possible to minimize to the normal size.

Reproduced on: 5.3.3f1 (7560298abfa5) (Ubuntu 14.04)