Can I know how to detect user is in page editor mode using code? This is because, I have a component, when user browses from page editor, it will search in master_index folder instead of web_index folder.
Please check with : if (Sitecore.Context.PageMode.IsPageEditorEditing)
also is working on Sitecore 6.6, it not depends on Sitecore 7.
Please check also this Sitecore blog post by Martina Welander.
To check if is normal page use: if (Sitecore.Context.PageMode.IsNormal)
To check if is preview mode use: if (Sitecore.Context.PageMode.IsPreview)
Also are others PageMode:
If you are curious you can check with Reflector or dotPeek this class: Sitecore.Context.PageMode from Sitecore.Kernel assembly.