Basic intuition question about WA_MinWidth/WA_MinHeight with WFLG_GIMMEZEROZERO

Hello,
I have a resizable window, and force default size of the inner window without the borders, so I have WFLG_GIMMEZEROZERO.
and I give the the default size with WA_InnerWidth,WA_InnerHeight (instead of WA_Width/Height). It opens with the right size.

But then, I also want the minimum size to be the same as the default size.
It doesnt work because WA_MinWidth/WA_MinHeight doesn't follow the GZZ way, it consider the borders are part of the size..
... so I have:

WA_InnerWidth, _machineWidth,
WA_InnerHeight, _machineHeight,
WA_MaxWidth, _machineWidth*_maxzoomfactor,
WA_MaxHeight, _machineHeight*_maxzoomfactor,
WA_MinWidth, _machineWidth,
WA_MinHeight, _machineHeight,

so I can reduce the window of _machineWidth/Height, minus the border size ... th'at not wahat I want.
It would be fine if I have the actual window border size with this I guess:
WA_MinWidth, _machineWidth+leftborderwidth+rightborderwidth,
WA_MinHeight, _machineHeight+topheight+bottomheight,

But those border siuze values are no-where.
... Or is there a proper way ?