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Ext GWT Premium Member
(RC 2) ProgressBar shows   if you pass null as progress text
If you pass null as progressText:
the progressbar shows " " as text:
ProgressBar bar = new ProgressBar();
While the doc for updateProgress() says:
* @param text the string to display in the progress text element or null
Thanks for the report. I've been able to replicate the issue and have committed a fix to SVN as r2615.
The fix for this bug has been included in the public release of Sencha GXT 3.0.0. Please try your test case again with this release. Although we're confident that this issue has been resolved, please reply here (or start a new bug thread linking to this one) if you continue to notice issues.