There are similar questions, but none address my specific issue.
I'm rather new to Android development and Eclipse but was able to follow the tutorials A OK.
In fact, I'm able to edit activity_main.xml from a tutorial, but now, in a test project I'm working on, I can't edit my new activity_main.xml (again, different project, same filename).
I created the file by right-clicking on the layout folder then selecting NEW > OTHER > Android XML Layout File. I was able to copy some of the other file so that my file now looks essentially like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
</LinearLayout>
When I type, the cursor moves around (looping through the text) but no characters appear on the screen. Again, in the other XML file I can edit with no problem.
I'm hoping that this is just some newbie problem.