Limit resizing a dialog


I'm trying to add a limit to how much a dialog can be resized by forcing the dialog's initial width and height if the new dimensions are smaller than the initial ones.
If I scale down the dialog beyond the initial size, an unpleasant flicker appears due to the script trying to resize back to a determined size.

Now, is there any other way to limit downsizing a dialog so that flicker is not visible?
Thanks in advance!

rollout ScriptWin "Script"
	multilistbox mlb_layers "List:" width:200 height:30 pos:[10,10]
	on ScriptWin resized theSize do
		x= theSize[1]
		y = theSize[2]
		mlb_layers.width = x - 30
		mlb_layers.height = y - 44
		if x < 230 do ScriptWin.width = 230
		if y < 440 do ScriptWin.height = 440
createDialog ScriptWin width:230 height:440 style:#(#style_titlebar, #style_sysmenu, #style_resizing)