Currently, if you have a ContentControl Content Template Resource inside of another Template, renaming the ContentControl Content Template in the Resources Panel causes:

1) The content of the ContentControl to disappear from the Stage
2) The Template to be removed from the list of available Templates to select from on the ContentControl.

See attached video (in the comments)

Repro Steps:

1) Download, unzip, and open the attached Studio Project.

2) On the Stage, under the 'My Order' Listbox, right click on it, and enter its ListBoxContainer Template.
This will open it in the Inline Dummy Template Editor.

3) Within the Navigator, identify the Element named 'ItemTypeIcon_ContentControl', and right-click on it to validate that it is using the ContentControl Content Template of 'ContentControl_Content_Icon_ItemType_Meal_Template'

4) Navigate to the Resources Panel, and under GlobalResources, select the Icon_Resources.xaml Dictionary merged under GlobalResources.

5) In the Resources listing, identify the 'ContentControl_Content_Icon_ItemType_Meal_Template' Resource, and rename it to any new name.

Observe how the Fork and Knife icon that was on-Stage has now disappeared and has been replaced with a 'ContentControl' text.

6) Right-click on the 'ItemTypeIcon_ContentControl', and navigate to the ContentControl Content Templates menu.

Observe how the Template is completely missing now.

7) Save all open documents, close and re-open MainPage.xaml.

Observe how the Fork and Knife icon has now re-appeared.

8) Within the Navigator, identify the Element named 'ItemTypeIcon_ContentControl', right-click on it, and navigate to the ContentControl Content menu.
Observe how the Template that was renamed is now present in this menu.

Expected Results: Renaming a Resource in-use doesn't break its display and availability.