XPLM_API void XPLMSetWindowResizingLimits( XPLMWindowID inWindowID, int inMinWidthBoxels, int inMinHeightBoxels, int inMaxWidthBoxels, int inMaxHeightBoxels);
Sets the minimum and maximum size of the client rectangle of the given window. (That is, it does not include any window styling that you might have asked X-Plane to apply on your behalf.) All resizing operations are constrained to these sizes.
Only applies to modern windows. (Windows created using the deprecated XPLMCreateWindow(), or windows compiled against a pre-XPLM300 version of the SDK will have no minimum or maximum size.)