Based on the information you provided it looks like you are trying to put a lot of content in a place that just is not enough, so visual glitches can be expected.
For example Firefox renders rather well when the width is insufficient, but if the parent div is for example 700 instead of 450 pixels wide it fails, too (due to the small Editor height of 150pixels).
In the given 450pixels (I took the dimension from your screenshot as I do not have another source of information) even the default set of tools is too much for both IE and FF.
In such a case I would suggest that you either use a smaller ToolsFile (like in the previous screenshot/scenario), or allow for a larger space.
the Telerik team