Moved from the Creative Cloud to the Flash Builder forum. They will be able to help you here.
Was there a solution to this?
Mine is doing the same thing. It opens in the mxml code editor - but no design tab available. Tried the Ctrl + ' and that did not work either.
I am having this same problem. I have started the "Flex In a Week" course and I am using the trial version of Flash Builder 4.7 on Windows 7 x64. Is there a solution?
Flash Builder 4.6 was the last version to feature a design mode. 4.7 discontinued it. Adobre has not updated flex in a wekk and I can't find any alternative educational materials past 4.6. if someone finds some please inform me!!