Description:
When editing the address block in a mail merge, it is very easy to corrupt the template using the editor in the wizard.

Steps to Reproduce:
1. Open the mail merge wizard
2. Go to the "Insert Address Block" page
3. Click "more"
4. Click "edit"
5. Click at the *end* of a line
6. Click the ">"

Actual Results:
The new tag is added in the *middle* of the existing one, corrupting it:

<A<Title>ddress Line 1>

Expected Results:
It should have ended up like this:

<Address Line 1><Title>


Reproducible: Always


User Profile Reset: Yes

Additional Info:
You must click at the *end* of a line, ie to the right of any existing tags. If you click on a tag, it is not reproducible.