This is the 4th tutorial for External Keyboard Helper and it is based on a real support question I got yesterday.
Let's say you have a compact bluetooth keyboard that doesn't have an Alt or AltGr button. However you want to use the US-International layout which has a lot of extra characters that can only be reached with AltGr and AltGr+Shift.
In this example I will show you how to sacrifice the (in my opinion rather useless) CapsLock key for a more useful AltGr key.
First I select the layout I intend to use. In this example the English (US-International) layout.
After that I enter the Advanced settings and
I choose to Customize keyboard mappings.
I choose to the create the Custom 1 layout using my selected layout as a base and
then Add a new key mapping.
Pressing the CapsLock key makes it read it's scancode which is 58 and I check the Keycode checkbox and choose Right Alt modifier as the keycode I want to map it to.
To make sure External Keyboard Helper ignores whatever the Android system things that the CapsLock state is I must also check Override special keys and make sure Always remap keys is checked.
That's it. CapsLock now serves as AltGr and I can access all the special characters that my selected layout has mapped for AltGr and AltGr+Shift even though my keyboard does not have a physical Alt or AltGr key.