We recently upgraded from Drupal 5.x to 6.22 and one thing noticed right away was that when the browser was taken off full-page the displayed page content would reformat into a very undesirable order. Previously the page would not resize and users could focus on only a small portion of the screen when in a windowed mode. This was true for mobile displays as well. Is there any 'simple' way to prevent this from happening? I realize this might be a css issue of which I am no expert. But because this entire site is generated and delivered via Drupal I thought I would ask others.
You need to add some css to various places in your theme, then. Give a 'width' attribute to the divs that contain the pieces of your page.
You may also be interested in 'min-width' and 'max-width' attributes.
Check out the drupal theming guide, or better yet, the README in your active theme's folder, to learn where and how to add the css. You don't have to be an expert- with just a little bit of time, this should be pretty easy.