Quickly clicking around withing the cells of a Inline Editable Grid causes an error dialog from the browser to show up. Screenshot provided. It can be reproduced from the "Sencha GXT Explorer Demo - 3.0.1"

Operating System : Windows 7, 64 bit
Browser : Integernet Explorer 8
GXT : 3.0.01

Test Case : No test case needed, since it can be reproduced from your explorer demo

Explorer Demo URL: http://www.sencha.com/examples/#Exam...needitablegrid
Inline Editable Grid Example

Just click between cells fairly quickly and after 3+ clicks, I usually can get this dialog to show up. Close it and it then can also be easily repeated.