As a followup to the previous article:

It might be better to just Exclude taskmanager because settings the Flag value to 0 might disable multi monitor support. To do this Create a new REG_SZ (string) under HKEY_LOCAL_MACHINE\Software\Citrix\CtxHook\AppInit_Dlls\Multiple Monitor Hook and name it Exclude. It’s value should be taskmgr.exe (case sensitive!).

I’ve also seen some issue where starting a Remote Desktop (RDP) session from within a Citrix session has some troubles with the RDP client’s window (the window “sticks” to the upper left corner or cannot be maximized). So it might be a good idea to include mstsc.exe as well in the Exclusion list (seperate values with ;).

The issues seem to have appeared with Hotfix Rollup 2.