QPushButton problems in DockWindow when changing text

When the text on a push button inside of an undocked dock window, the button is dropped lower on the UI and the bottom half is cut off. Upon redocking the dock window, that button's graphic is changed into the graphic of a tool button. Changing the text once more while the docked window is docked will return the button to its normal push button state, but undocking and pressing the button before it has been reset will not fix it, and the problem repeats any time that the dock window is undocked.

The attached zip contains a simple example.