1) In applications that use "hot key" sequences, do not use key combinations of ALT+<alphanumeric character>. Use other key combinations that are not affected by this defect.
2) Processing the key sequences within an editor widget seems to mitigate the problem. Running the following code in a GUI procedure editor shows the alphanumeric characters associated with the ALT key not being discarded:
DEF VAR cMyBuffer AS CHAR NO-UNDO.
DISPLAY cMyBuffer VIEW-AS EDITOR SIZE 50 BY 10.
ON 'any-key':U OF cMyBuffer DO:
SELF:SCREEN-VALUE = SELF:SCREEN-VALUE + SUBSTITUTE("&1 -- &2 -- &3~n", LASTKEY, KEYLABEL(LASTKEY), LAST-EVENT:LABEL).
ENABLE cMyBuffer. WAIT-FOR "Q" OF cMyBuffer.