I never understood the benefit of writing the ExplicitLeft / Top / Width / Height properties for TControl and descendants, which were added in Delphi 2007, to the dfm files. They store the control’s position and size before its Align property was set to something like alClient or alRight, so they can be restored later. That’s useful if you change these by accident or double click on the Align property to go through the possible values, but as soon as you save the form, you don’t really need them any more. Even worse, they seem to change often with no apparent reason and therefore clutter a dfm file’s diff with changes that nobody is interested in.
read on in the blog post