With findwindow () found tecplot handle, then setparent to qt widgets, but embedded in the tecplot many button failure, only the top menu bar can be used, it is strange that drag the child window that failure into active window, button can be used again, inquire of god this how to solve?

 HWND tec=FindWindow (L "QWidget," L "Tecplot 360 EX 2016 R2");//L "Tecplot 360 EX 2016 R2" 
HWND tec_qt=(HWND) UI - & gt; Widgets - & gt; WinId (); 
SetParent (tec, tec_qt); 

This button is invalid, the menu bar on the top of the only child window button available

Dragged into the active window can be used