I have looked through the forum for an answer to this and have seen similar posts but not the answer...

I keep having panels where at some point the content is larger than the area so the vertical scroll bar appears. This is fine. However, when the vertical scrollbar appears it decreases the view area by some amount of pixels and the result is the horizontal scroll bar appears. This is not fine.

Can someone tell me what I'm doing wrong? More importantly, how can I avoid this?