Following bug detected with Internet Explorer 9. I do not know how other browsers respond to this error, since I've only tested on Internet Explorer.
1) Open Internet Explorer with an empty tab or google.com
1.1) Open Construct2
2) Open example -> Families.capx
3) Open example -> Physics - vehicle.capx
4) Go to layout (Families)
4.1) Run layout -> working
4.2) Close tab with preview
5) Go to layout (Physics)
5.1) Run layout -> error
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Meldung von Webseite
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Javascript error!
F?r die Eigenschaft "prototype" kann kein Wert abgerufen werden: Das Objekt ist Null oder undefiniert
localhost/data.js, line 1
This is either a bug in Construct 2 or a problem in a third party plugin or behavior - please report it to the developer!
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OK
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If you close all tabs and test it again, the preview of the layout working like a charm. Also if you leave the window (preview) open, the second preview is working.
I hope everything is understandable <img src="smileys/smiley2.gif" border="0" align="middle" />