Setting the minimum size for reaper's plugin GUI windows

[OverToneDSP]

I'm developing / porting some VST / AU plugins to Mac OSX and Windows. I would like to be able to set the minimum size for the host plugin GUI Window provided by reaper (such that the user cannot re-size it to be smaller than the plugin GUI). This is particularly something I would like to solve for Mac VST plugins. Attempting to set various parameters on (for example the host-provided WindowRef for 32Bit Mac VSTs) appears to have no effect. Is there a way either within the VST spec or a Reaper-specific way in which the plugin can set / hint the minimum host GUI window size, or possibly stop the window from being user-resizable, and have that recognized by reaper?)