The latest version makes working with dual screen setup impossible. No window position is stored, every click leads to the predefined (completely wrong) position. That's true for source code, object inspector, messages etc. - every window. For instance, moving and sizing the source window to the right position and running the code with a debug point puts the window back on the other screen.
Lazarus 1.5 rUnknown FPC 3.0.0 i386-win32-win32/win64
(rUnknown? Just read from svn, at revision: 49937; double-checked the issue positively with fpc 2.6.4)