I found an odd behaviour that I can't tell if it's really Files related or actually Budgie such that a file type gets its default application changed just by using context-menu option of "Open With Other Application".
To reproduce one must use a file type that has a default application defined NOT by the user but by the system and select one of the recommended applications to open it. For example, I select to open a PDF file with Vivaldi browser and afterwards the systems stops opening PDF with Document Viewer.
If one instead uses the "Properties" option of the context-menu (right-click) and changes the default application for that type, then the context-menu option "Open With Other Application" starts behaving 'normally', i.e, opening but not changing. In the PDF example, after I set Document Viewer as the default application, then I could choose to open it once with Vivaldi and still have PDF opening normally with Document Viewer via left-click.
Hope I got it clear.
