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In Visual Studio Options - Text Editor - File Extension you can map your custom file extension to a Visual Studio editor.
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Next, we are going to define "C/C++ user defined keywords":
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Also, make sure the "usertype.dat" file is copied to "C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE" and not "C:\Program Files\Microsoft Visual Studio 11.0\Common7\IDE"
usertype.dat
Code: Select all | Expand
DEFINE
WINDOW
DIALOG
FONT
ACTIVATE
FROM
TITLE
COLOR
SAY
ON
RIGHT
CLICK
VALID
RESOURCE
CENTERED
Until we get a complete usertype.dat, remember that everytime that you modify it, you have to exit and reload Visual Studio to activate it.
And here it is the result
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