I have a PC with Linux Mint 19.2 installation that I set up a while ago. For that system, among other similar modifications, I figured out a way to remap one specific key combination: Meta + ~ produces a ` (grave accent). Recently I built a new PC with a fresh installation of linux Mint 20.2. I carried over all of the modifications that I thought I'd done to the old system into the new one. This includes: - /usr/share/X11/xkb/keycodes/evdev - /usr/share/X11/xkb/rules/evdev.xml - /usr/share/X11/xkb/symbols/us All my modifications work on the new PC, apart from the grave accent one. Apparently, this particular setting is done elsewhere. I checked the modifications of the desktop keyboard mappings: dconf dump does not reveal anything related to the accent key. Basically, I need to reverse engineer how I managed to remap that key on the old system. It would be really great if someone could give me a hint either how to configure such mapping or where to look for the possible other modifications I could have applied on the old system outside of what is available in /usr/share/X11/xkb/.

Another name for the *keyboard viewer* is the *special characters keyboard viewer* developed first in OSX, Youtube video here . It is used to visualise the dynamics of typing different key combinations in first-level/second-level/... ways. **Warning** I do not want to have virtual keyboard like shown by the confused answers in the thread Onscreen keyboard? (like OSX's Keyboard Viewer) where the title is about *Onscreen keyboard viewer*, not virtual keyboard. I tested Florence/Onboard/xvkbd/... but the virtual keyboard is risky because it can misconfigure your keyboard settings, forcing you restart your system, so no to virtual keyboards. You can view static keyboard viewer by *Language menu* at top > *Show Keyboard Layout* > Output, or from the settings, *Region & Language* > select an input source > click on the keyboard button in the lower-right-hand corner; this will display the keyboard layout in Fig. 1. This view is static, *i.e.* it displays all accessible characters at once; it does react to key-presses, but only by highlighting the depressed key(s). It would be easier to understand the layout if it showed the characters accessible with the current set of modifiers: *e.g.* the P keycap would show only p by default, and would would change to P if you pressed Shift, ö (on a Dvorak layout) if you pressed AltGr, and Ö if you pressed ShiftAltGr. In OS X, the feature has been 5-10 years, but I have not found anything builtin in any Linux distro nor any program in apt by the following searches. apt search viewer | grep keyboard I think Gnome 3.22 can support such a tool in Linux. I need the tool to better visualise how to typo A with dots/... (ä, ö, ...) in Linux. Fig. 1 Static keyboard layout of Dvorak, an example, Fig. 2 Example of dynamic keyboard viewer in OS X (source ) but video here OS: Debian 9 Gnome: 3.22