wxWidgets strange modal dialog crashes

Recently, I wrote one program with Code::Blocks version 12.11 and wxWidgets version 2.8.12. Logic of the program required invoking modal form (inherited from wxDialog, created with wxSmith). Once, during debugging, I found that the program continiously crashed after showing this modal form. The crashes usually occured either just after constructing of this dialog instance, or after a few seconds of this dialog being active. I revised all places in the source code which were somehow related with construction of this dialog, and with passing parameters of its construction and initialization. But I was unable to find any error(s) in the source code itself. At last, I got a flash of inspiration: I actually created this dialog from secondary ("worker") thread. After reimplementing this fucntion as running in the main thread (via combination of auxiliary window, SendMessageW with WM_USER and pointer to the structure with function parameters packed into WPARAM message argument, and MSWWindowProc functions), all crashes stopped. So the error was not in some line of the source code itself, but in the wrong architecture and lack of attention to this fact. The accompanying factor was that in previous version of the program, I used simple standard wxMessageBox function in that place. wxMessageBox apparently invokes WINAPI MessageBoxW function, and this works fine from secondary thread. But when I changed this to invoking of custom wxDialog form, in order to gain additional functionality, crashes began, and it took some time for me to understand where the problem resides.