Gens Emulator 2.14 after switching back from fullscreen the app can never be moved around by dragging at the title-bar

0.4.8-RC-16-gaf545fe
Gens Emulator 2.14 from rapps
VBox 4.3.12 + VBEMP + inbuilt Mesa

Reproduction steps
-have desktop resolution set to 800x600 32bpp
-Start the app
-switch to full-screen via alt+tab
-switch back to windowed via alt+tab
-the app will properly switch back

Expected behavior
-It should be possible to move the apps window by dragging it at the title-bar

Observed behavior
-It can not be dragged around. Its position is carved in stone. Neither minimizing nor maximizing does help.
0.4.8-RC-16-gaf545fe__gens.log

Without switching to fullscreen before, the app can be moved by dragging its titlebar as expected.