I have my keyboard set to "English US - AltGr International" in Ubuntu system wide so that I can enter words from Latin, Sanskrit, and a slew of other languages properly when needed. I noticed that for some reason every QT based application (not just KDE) was not working with one particular diacritic that is very common in Sanskrit: the "DOT BELOW" UNICODE characters. Instead the keystroke ("AltGr + _") does not register and it just prints the next keystroke as is.

Non-QT programs such as LibreOffice, Inkscape, and xterm do not have this problem so I have isolated it to just QT applications. It is also not a display error as a text file created in vim in xterm with will display the characters in konsole, they just cannot be produced. I have tried enable the compose key as well, which also does not work.

This is a pretty major problem because someone, somewhere (probably someone who types transliterated Vietnamese) probably has this same problem because that language also uses "DOT BELOW" diacritics as well.