Tk_MainWindow man page
Tk_MainWindow, Tk_GetNumMainWindows — functions for querying main window information
#include <tk.h> Tk_Window Tk_MainWindow(interp) int Tk_GetNumMainWindows()
- Tcl_Interp *interp (in/out)
Interpreter associated with the application.
A main window is a special kind of toplevel window used as the outermost window in an application.
If interp is associated with a Tk application then Tk_MainWindow returns the application's main window. If there is no Tk application associated with interp then Tk_MainWindow returns NULL and leaves an error message in interpreter interp's result.
Tk_GetNumMainWindows returns a count of the number of main windows currently open in the current thread.
application, main window
Tk_GetNumMainWindows(3) is an alias of Tk_MainWindow(3).