Start Writer, open the sidebar, select the Stylist, and move the mouse over some entries. The console shows: soffice.bin: /home/ht/Sources/libreoffice/vcl/source/app/dbggui.cxx:36: void ImplDbgTestSolarMutex(bool): Assertion `ImplGetSVData()->mpDefInst->GetYieldMutex()->IsCurrentThread() && "SolarMutex not owned!"' failed. Gtk-Message: 16:30:28.633: GtkDialog mapped without a transient parent. This is discouraged. Does not happen for kf6/gen/gtk3. Version: 26.2.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: 7d2b92d0e78751ac00d25dd312f7bc77abe96b4e CPU threads: 32; OS: Linux 6.16; UI render: default; VCL: gtk4 Locale: en-US (en_US.UTF-8); UI: en-US Calc: threaded