Hmm, I'm not sure how to edit my previous post. I believe I've solved the problem; for some reason rebooting the computer and reloading the project fixed the issue.

However, now I can't get GLEW to work. I've made sure to include it before any QGL includes, and the project builds fine if I don't call any glew functions. But if I have glewInit in the initializeGL function, QTCreator complains:
Qt Code: 
  1. glwidget.obj:-1: error: LNK2019: unresolved external symbol __imp__glewInit@0 referenced in function "public: virtual void __thiscall GLWidget::initializeGL(void)" (?initializeGL@GLWidget@@UAEXXZ)
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I'm not sure what's off here. I have the #include in the right place and all. I had glew32.lib in C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\lib, but the error persisted even after I moved it to C:\Qt\4.8.3opensource\lib. Do I have to set up the linker somehow?