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    Bug 
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    Resolution: Done
- 
    P1: Critical 
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    Qt Creator 3.0.0-beta
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    Ubuntu 13.04, QtC 3.0 and Qt5/stable built from git (debug versions).
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        qtbase 72a7882cec07a9ad187c9e1772fb08f59a4b9519
Open some source, try to fold code by clicking the little arrow on the left of the text editor – nothing happens.
Now restart Creator with "-noload Welcome", try the same and it works.