I've discovered strange behavior of LXterminal 0.1.11. Steps to reproduce:
1) open lxterminal;
2) right-click on window (context menu shows up);
3) click on window or press 'Esc' (context menu disappears);
4) start 'mc';
5) cursor in mc follows mouse!
When I double-click on window in step 3 then mouse behaves as it have to.
fixed in commit 43735c84 thanks to geekless' patch.