When the option is set for multiple display in Coherency mode, the start menu on the monitor on the left does not display. Windows begin to disappear (become cropped) when being dragged to top or bottom of the external display. I am using a 17" Mac Book Pro running 10.4.8 connected to at 17" LCD connected to the DVI port and running Window's XP.
Coherence seems to work by setting Windows to use a single virtual screen that spans both monitors, and then doing something like a cinema "green screen" trick to mask out everything but the active windows. The catch is that the virtual Windows screen has to be rectangular - windows doesn't see two independent screens. The practical upshots of this are: 1. Since the windows screen is always a rectangle, Coherence messes up if, in the "Monitors" control panel under OSX, your screens are not lined up side-by-side. If you have a laptop+extenal monitor, its quite likely that you've set the monitor arrangement to reflect the physical layout - with the external monitor positioned higher. 2. 17" MBP = 1680x1050 pixels, typical 17" LCD =1280x1024, so you're always going to lose 25 pixels or so off the bottom of one screen or the other. I'd guess that whichever screen has the menu bar determines the max height of the windows screen. 3. Coherence excludes the apple menu bar from the screen area, so you lose 20-or-so pixels for that. I guess they don't want to lose windows under the menu bar - plus that means having the Windows task bar at the top of the (windows) display sits it right under the menu bar, which is pretty convenient. 4. If you choose "exclude the dock" (Parallels -> View -> Customise -> Coherence) then the dock area gets excluded from BOTH screens. For best results (IMHO), go into the apple monitors control panel and line up the bottoms of your two screens (Its a fiddle- I had to ctrl-drag to stop them snapping to a different arrangement). Then use Parallels "View -> Customise Coherence -> task bar -> relocate automatically" or manually shift the windows task bar to the top. Edit - Duh! that is probably only valid for my combination of monitor sizes- you may have to use trial and error - thing to remember is that the menu bar in the "Displays" panel is not to scale...
