["Alt+R" was shorthand for "invoking the keyboard accelerator in the appropriate manner to execute the item where the R is underlined, either pressing a plain R if invoked directly as a pop-up context menu, or Alt+R if invoked via the File menu." I guess I need to write even more formally now. -Raymond]
I didn't even think about the File menu. Actually, even in that menu, pressing Alt closes it. However, if you open the File menu with Alt+B (again, Dutch system), then shortcut keys work regardless of whether you release the Alt key. Both (hold Alt, press B, press H, release Alt) and (hold Alt, press B, release Alt, press H) work and do the same thing. That takes extra effort to get right, I never noticed it before, and I'm impressed. What also surprises me is that in the File menu, the Properties item is called Eigensc_h_appen, with H as its shortcut key, and appears directly below the Rename item. In the context menu, it is Eigens_c_happen, and there is a separator between the Rename and Properties items. Other menu items also differ in the chosen shortcut keys. I guess that's because the File menu also has an extra Close item at the very bottom taking up one fixed shortcut key, so it would look bad if the Properties item had a separator directly above and below it, and the shortcut keys for the other items get adjusted so that they don't conflict with Close.