The DlgAreaU resize method can create slightly over-size margins on the left & bottom of the Dialog. To correct for this the DlgAreaU class has a CorrectionFactor attribute set by default to 1.05 which in tests appears to neutralise this effect. If your dialogs have over (or under) sized margins, you may be able to correct this in your code by overiding the Correction Factor like this (for example):
U=.DlgAreaU~new(self) U~CorrectionFactor=1.05
You will have to experiment to find the apropriate setting for this attribute.