I have a dual-head setup, with one monitor rotated (using xrandr). The rotated monitor resolution is 1280x1024, which, when rotated, turns to 1024x1280. When maximizing a window before rotating the screen, everything works well (the window is resized to the full size of the screen). After rotation, however, maximizing a window causes it to resize horizontally to the full size of the screen (1024 pixels), but the vertical size falls short of the full screen. While I don't have an exact measure of the vertical size, it looks like 1024 pixels.
Possibly caused by an application that fails to update its struts when the screen size is modified (e.g. the xfce4-panel is not randr 1.2 aware) Please attach the output of "xprop | grep STRUT" for each of the dock windows you have.
I have no docked windows on the rotated monitor. I tried adding a bottom panel, to see where it goes, and it was positioned correctly (i.e., touching the 1280 pixels border). I believe this suggests that the desktop itself is aware of the rotated monitor's dimension, but the window manager is (perhaps) at fault.
You don't necessarily have to have docks _on_ the rotated window because struts (and partial struts) are relative to the non-xinerama screen (ie they apply to the whole screen made of all smaller displays) - Actually, the more I think of it the more I am convinced it's the panel that screws the struts. The desktop itself couldn't care less about struts so that's irrelevant here. Easy to test, exit all panels (xfce4-panel --exit) and do the same test. Oh, btw, what version of xfce are you using? Xfce 4.4 is not ranrd 1.2 aware and will never be.
1. Killing the panel did not fix the problem. I only have one panel at the top of the screen. 2. I'm using Xfce 4.4.3 on ArchLinux, so it's mostly a vanilla version. I don't know what constitutes as RandR compatibility. I only know that rotating the screen with xrandr gives (mostly) the desried results under Xfce. The only two problems I have are this one (maximized windows) and weird font size issues (see http://bugzilla.xfce.org/show_bug.cgi?id=4250).
(In reply to comment #4) > 1. Killing the panel did not fix the problem. I only have one panel at the top > of the screen. > 2. I'm using Xfce 4.4.3 on ArchLinux, so it's mostly a vanilla version. ^^^^^^^^^^ So that's normal, the code is not there in xfce 4.4. Switch to xfce 4.6 (once it's released ^_~)