I am facing a weird interpretation problem with Editable TreeGrid and IE8/9

The problem appears randomly after an edit or after expanding an item : the line edited/expanded and/or the root line is rendered empty (all other lines are not altered).
Resizing has no impact on the rendering but scrolling does bring the rendering back to normal like IE was forced to reinterpret or refresh. Forcing refresh/repaint/rendering GXT-side gives no result (code is correct and executed but with no result.

Introspection of the hmtl/css code browser-side show that when a line is temporarily rendered empty through this bug the corresponding div element is actually empty. The bug never occurs with firefox or chrome but unfortunately I cannot force my client to forsake IE.

Last but not least, since it's an Editable TreeGrid taking advantage of all the power of that component, completely re-writing seems unrealistic.

Thanks in advance for any help!