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XPLMSetWindowResizingLimits

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.)