Linux Mint with 2 screens - jumping windows

[tudi_x]

hi!
i am using Lazarus 1.6.4 64bit on Linux Mint (Matte).
i have 2 screens (main 1200x800,secondary 1600x1200).

having source editor on my secondary screen and switching the unit with the mouse would trigger the move of the source editor to the main screen.
same behavior for the messages box when there is an error.
please advise if this replicates and if it is the intended behavior.

thank you

[tudi_x]

i restarted Lazarus - behavior is not happening but for the messages window that moved to a new position in the secondary screen.