For anyone considering installing AIAB r10.5 bleeding edge version 'aiab-20070528.zip' and AMOSPro, here is a description and a workaround for the 'Drawer locks when opened' Bug.
WinUAE 2.4.1 (2012.05.09)
Workbench 3.1
AIAB r10.5 bleeding edge version 'aiab-20070528.zip'
AMOSPro All versions
Note: This only applies if AIAB is installed and AMOSPro is installed to Hard drive. AMOSPro runs fine from floppy.
When you try to open the AMOSpro drawer (see first picture), The drawer that opens will be locked in that size and position and no icons will be visible. You may also encounter other desktop problems.
To resolve the problem, shut down your emulation and restart it. Do Not open the AMOSPro drawer.
Instead open DOPUS and delete 'AMOS_Pro.info' (see second picture). You will now have access to the drawer and AMOSPro.
[Update] You will also need to delete the 'APSystem.info' and 'Productivity2.info' files from the AMOS_Pro directory. These give the same problem. The other drawers seem to be fine.
You can find the AIAB r10.5 bleeding edge version 'aiab-20070528.zip' in the downloads section under the 'Ultimate Amiga Emulation Downloads' category.