A bit like issue #15007 in reverse. Throughout LibreOffice, when you try to close a document with unsaved changes, the app prompts you with a confirmation dialog. On some platforms, it uses a GTK dialog to do so. In that case, it should also apply the "destructive-action" CSS class/styling to the most dangerous button in that dialog, "Don't Save" See also: https://developer.gnome.org/hig/patterns/controls/buttons.html#button-styles https://docs.gtk.org/gtk3/const.STYLE_CLASS_DESTRUCTIVE_ACTION.html
We do this already since 7.3, see sfx2/uiconfig/ui/querysavedialog.ui which is the general file save case. and under gtk the "Don't Save" is highlighted with the red danger background. (also seen in svx/uiconfig/ui/deletefooterdialog.ui and svx/uiconfig/ui/deleteheaderdialog.ui which are undoable actions)