Sets the default size of the window to width pixels wide by height pixels high. Setting either parameter to -1 will use the "natural" size for the window. The "natural" size is the size of the window after its child widget has been added and shown and before any other sizing has been done.
Using set_default_size() simply sets the size of the window. It does not set any restrictions on whether or not the user can resize the window later. This method acts as if the user had resized the window. Unlike set_size_request() , the user may shrink the window below the height and width passed to this function.
This method respects any geometry hints that have been set for the window. If the height and width given do not match the geomety hints, the window will be clamped to the nearest acceptable dimensions.
Windows may not have a size smaller than 1 pixel wide by 1 pixel high. If 0 is passed for either argument, the value will be changed to 1.