Hover 1.0 from rapps does leave the taskbar visible when pressing F4 to enter fullscreen

0.4.12-RC-43-g6f651b6 gcc dbg lin
VBox 4.3.12 + VBEMP, no additions, desktop resolution 800x600 32bpp

Reproduction steps

• install and run Hover 1.0 from rapps
• enter ingame gameplay
• press F4

Expected result
The game switches into fullscreen and the taskbar should be hidden
2k3sp2_ok_doesProperlyHideTheTaskbarOnF4.webm

Observed result
The game switches into fullscreen but the taskbar remains visible erroneously

(win32ss/gdi/eng/pdevobj.c:522) PDEVOBJ_bSwitchMode, ppdev = E177D008, pSurface = E199A8C0

(win32ss/gdi/eng/pdevobj.c:585) leave, ppdev = E177D008, pSurface = E1A57490

(win32ss/user/ntuser/display.c:868) err: BitCount New 32 Orig 32 ChkNew 32

(win32ss/user/ntuser/msgqueue.c:846) err: Remove Window Messages E1A50440 From Sent Queue

I suspect the bug to be in our explorer_new. I have not tested, but would guess it does work properly in case we would use explorer_old or explorer_2k3sp2.