Cannot typing in DC in Linuxmint

Hi,

I'm using DC in my box (LinuxMint16). Everything is ok, except in DC I cannot type any character.
For example, if I go to search (Alt-F7) then type some letters to seach, only first typed character occured. The rest was ignored.
In twin - panel, if I type something, with expected to run some command, also only first character occured. if I try to click mouse, then type again, I am again able to type ONLY 1 letter.
This problem occurred no matter I choose anything for Keys mode (Quick search, Filter, Command)
This problem occurred only if I run with non-privileged user. Running with root is ok.
This problem occurred in all version I tested (0.5.6, 0.5.8, 0.5.9, 0.6.0, ). IT was not occured before, when I use Ubuntu. Just Mint meet the problem.
Did I do something wrong?

Please help.

I didn't find the right solution from the Internet.

References:-
https://doublecmd.sourceforge.io/forum/viewtopic.php?f=6&t=2289
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Thanks