"Full screen" option does not work if window is already maximized

[dziemborowicz]

The current development version of Hourglass at 7163624 has a bug where selecting the "Full screen" option does not work if the window is already maximized.

Repro steps:

1. Launch Hourglass.
2. Maximize the window.
3. Right-click and set "Full screen".

Expected: Window should cover the entire screen (taskbar should not be visible).

Actual: Window remains maximized but does not cover the entire screen (taskbar is visible).