Fix unnecessary inclusion of glibmm/threads.h. This can be resolved by ensuring that glibmm headers always preceed glib.h headers. Same applies with gtkmm/gtk+ etc
Adding inclusion of config.h where needed for threads.h check.
Added configure/ifdef guards to only bring in the needed #include if glibmm has it.
Correct to compile against recent gtkmm, including updated macports versions. Fixes bug #1179338.
GTK+ 3: Use orientable widgets
Clean up a few Gtkmm orientables
Clean up all remaining false warnings from Gtkmm
Header cleaning
Fix documentation
Fix for 938349 : Compile error in spellcheck.h when aspell is unavailable
Fix for 934721 : Convert SpellCheck dialog to a dockable dialog