I am using an application that has important operations mapped to the PgUp and PgDown keys, but my keyboard doesn't have these keys (I'm using a ChromeBook Pixel 2015, running Linux Mint 18.2). I know I can map a certain keycode to the PgUp and PgDown keysym using
xmodmap, but I can't give up any other keys permanently.
Is there a way to map the sequence Alt+Up to PgUp and Alt+Down to PgDown? Is there a better way to achieve this?
EDIT: I have used the command
xmodmap -e "keycode 111 = 0xff52 0xff55" to set shift + Up to PgUp but I am still interested in a general solution.