A user here had this problem which was strange enough that I thought I'd share it, and the fix:
Q Why can't I see an undocked property window in Mentor DxDesigner?
A The problem was due to the user setting his second LCD monitor, Display #2 (on the right of Dislay #1) to be used as the Windows "Primary" monitor.
The DxDesigner appication needs to launch in the first LCD monitor and assumes it is the primary display. Once the user sets the primary monitor to
the right display (display #2) the DxD application when launched in that display and then the user tries to view the Properties window in an "undocked"
mode, this properties window does not appear.
Once I went into Display Properties > Settings > and set the left monitor#1 as the "Primary" monitor everything worked fine.