Unit QT4 seems to be missing. I get the following error when I try and build.
lcl/include/qt/cairolcl.inc(2,3) Fatal: Can't find unit qt4 used by CairoLCL
Switching the target to GTK-2 works, but GTK-2 is too slow to be usable, so it's not a solution.
This problem did not exist when I was using 1.2RC2.
QT4 is not delivered with Lazarus. It must be installed separately before you can use LCL-QT.
Nothing about package dependencies has changed since 1.2RC2. Something else is going on in your system (again).
I also wonder why your GTK2 is so slow. Here it is about as fast as QT.
GTK-2 graphics are known to be slow.
I'm back on 1.2RC2 and had the same problem.
QT4 has been installed on my systems from the start. The problem seems to be the old root access issue. As soon as I gave my user write privileges to the lazarus directory AND configured Build Lazarus for Clean All, then everything worked fine. Now, I can set Build Lazarus back to its default settings and it all builds normally. It seems to require the Clean All setting only once to get the QT4 unit built.
And I don't believe there is anything going on in my system (again), especially considering that these same issues have shown up on three different systems, all installed by Laz Project packages, be they debs or RPMs, with root ownership. I do think my situation is unusual in that I use Linux, don't build Laz from the svn, use the LuiCairo package, and target QT.