You can use Adjust Window [Resize to Fit] to adjust the original layout. This step can be used on the close button of the dialogue box
Is there no way to stop the original re-drawing/sizing?
I watched a demo on Modal dialogue boxes on Youtube and they didn't have the original layout re-drawing/sizing!
I have been concentrating more on the database design and only getting round to learning about how layouts can be manipulated.
Presumably you are using windows with windows maximized. You can either do as advised or don't have the windows maximized to begin with.
For an example of code that resizes the original window, you can examine scripts in the Known Bugs List that do this.