Happened to me on all linux distros I'm using (linuxlite 32&64bit, KDE neon 64bit). Reproducing the problem is just easy: Open a blank project, then on main form keep changing Font.Quality property. You should see what experienced. On windows this doesn't happen. Most lazarus linux-version installed in our workshop is 1.8.2. And I've checked with version 1.6.4 (KDE Neon 64bit) the same problem exists. So this isn't new.
We're hoping for workaround while waiting next maintenance release. thank you
Update (2018.04.06 14:46):
with strace startlazarus returned (console) messages:
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_font_description: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_text: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_pixel_extents: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_text: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_pixel_extents: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Pango-CRITICAL **: pango_layout_get_text: assertion 'PANGO_IS_LAYOUT (layout)' failed
(lazarus:4101): Gdk-CRITICAL **: IA__gdk_draw_layout_with_colors: assertion 'PANGO_IS_LAYOUT (layout)' failed
repeatedly, until I close lazarus main window (after "busy" dialog). Don't know what to do next.
Please kindly help....