Property editor does not update properly after deleting a texture which was applied to material e.g. as a diffuse map.

Steps to reproduce:

1. Create a project 
2. Add view3D
3. Import the attached image Water1.jpg
4. Drag and drop the image to the cubeMaterial in the navigator
5. Delete the created texture
6. Choose cubeMaterial from the navigator
7. -> As seen in the 3D Editor, texture map is removed but the properties pane is still indicating that texture is applied to the material as a diffuse map (see picture)
8. If diffuse map drop down menu is opened and [None] is selected, texture will be removed from the list of selectable items