Thanks for the additional information.
Here is what I found.
I made WinStore application and tried to reproduce your issue. Added some controls and tried to access them from the code behind. Then I found the indeed the Intellisense can't complete them.
In order to check that JustCode is not the culprit I disabled it from JustCode > Help menu.
No intellisense again.
I continued to work over the application and at some point Intellisense started working as expected. Turned on JustCode which didn't prevent the auto completion. Restarted the solution and again everything was fine.
My conclusion is that this is a VS issue and JustCode has nothing in common with it.
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