Can't make friends JUCE and GTK2+

Hi! I’m developer of LSP Plugins
My plugins currently use GTK2+ UI that works fine as standalone version, under Ardour and Carla.
But when trying to start the UI under JUCE audio plugin host example, I can not do anything with GTK widgets.

The main reason is because widgets do not receive ‘button-press-event’. I’ve already found the code that sends the corresponding XEvent to the child window but still my GTK widgets do not receive it. The second strange moment is that they always receive ‘button-release-event’.

The same problem is with AMSynth, that is GTK2, too. Currently I have already no idea what happens. JUCE sends X events but they suddenly disappear and don’t reach the target child window of the plugin editor.

Please, if you have any ideas how to fix it, let me know.