Browser Compatibility - A pain

In one of my current projects, I was asked to look into the javascript issues to identity what it takes the current script to make it work for firefox. There were a few learnings such as:

• ParentElement property doesn't work properly in all the cases
• Modal dialog boxes aren't supported in most of the browsers. To overcome this issue I worked on couple of work-arounds that I'll be posting after I do some initial tests on that. It took me more than 4 hours to work around on modal dialogs where parent page takes some action based on return value.
• It's better to use Rows and Cells properties rather than ChildNodes to traverse through table elements.