Using R# 6.0, whenever I have a standalone class file that doesn't match the filename, it gives me the option to rename the file to match. It does not offer that option when renaming a class that is within .aspx files.
Create webform called Test_One.aspx with codebehind file
In the codebehind file, select Partial Class Test_One and it will give you the option to change it to TestOne
With the class name selected, shouldn't it give you the option to change Test_One.aspx, Test_One.aspx.(cs/vb), Test_One.aspx.designer.(cs/vb) to match - and all corresponding usages, but it doesn't.