I can't replicate this with the Ctrl key in the regular Firefox release. Does it work if you middle-click the bookmark with the mouse scroll wheel?

You can try the Firefox version from the official Mozilla server if you currently use a version from the repositories of your Linux distribution to see if that works differently.

Middle-click works (although there is no scroll wheel). Thanks for that.

The official Mozilla version – maybe, but not this evening.

Ciao – Peter

Just to be sure, did you try Firefox Safe Mode to check if an extension is causing this issue?

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Sorry, when starting in safe mode there is no bookmarks toolbar anymore. Instead I'm able to open a bookmarks sidebar. There is no problem when hitting ctrl key. But this holds true even when running FF in unsafe-mode.

But when opening a context menu, it also closes the moment ctrl is depressed (regardless whether in safe moder or not).

By the way, this is true also when using Thunderbird. However, when using other software (e.g. Evince, Gedit, Gimp, Nemo, Nautilus, a terminal window), their menus survive a ctrl hit.

Being stumped, Peter