tilde, acute not working

I'm working on Linux/X11, with dead keys enabled, using
jdk1.4, german keyboard. It's not possible to enter
tilde (~) and acute (^) characters in jedit. This would
be accomplished by pressing AltGr +, then Space for the
tilde, and ^, then space for the acute.
It is however possible to enter combined characters
like ă or ô with those same combinations. It seems to
me like a bug in Java 1.4, and I have found fitting
bugs in the java bugparade. Maybe it is possible to
incorporate workarounds into JEdit in the meantime,
until those things are fixed.