A little update. In the upcoming SP1 for EPiServer CMS R2 we have made a fix so that the dynamic content window will automatically resize to try to fit all properties contained inside it. Depending on the size of the content and the size of the screen it might not be possible to fit the entire control, but an attempt will be made.
Hopefully that will get rid of your annoying scrollbars.
EPiServer CMS development team
Will it be able to handle custom edit controls as well as standard properties?
Yes, that was the goal of the fix. What we do is that we check the size of all controls and chang the width of the dialog to fit them, if possible. The width will of course never get wider then the screen.
It's somewhat dependant of the html of course, but unless there is something very "strange" it should work fine (we hope ).
Could you give us a hint with some code?
Not knowing much I would try with some regular css changes. Could possibly have something to do with IE hasLayout property.
overflow: hidden and a width on the panel would trigger hasLayout.
The easy way to trigger is zoom: 1.
But I am only guessing.