Please describe the problem:
In indexed color images, if the color map is changed, previews (in the 
toolbar, in the window's titlebar, the preview used in the Recent Documents 
history, and even in the Edit Colormap Entry window) do not get updated. 
 
Another edit (e.g., paint with the paintbrush) must be done for these previews 
to become updated.  (Fortunately, the file's "Saved" status is updated, so a 
"*" appears in the window's title, and File->Save / Ctrl+S work properly to 
save the image.) 
 

Steps to reproduce:
1. Create or open an image that's in Indexed color mode  
2. Select "Colormap" from the Dialogs menu  
3. Change one of the colors used in the picture (either by entering a new hex  
code in the colormap dialog, or double-clicking a color, editing it in the  
Edit Colormap Entry window that appears, and dismissing the Edit Colormap  
Entry window with its "OK" button) 
 

Actual results:
Notice the colors change in the image itself, but not in the thumbnail  
preview of the image used: (1) as the image's window/titlebar icon, (2) in the  
Display Navigation display, (3) in the Undo History previews, (4) in the 
navigation pop-up's thumbnail (accessible via the four-arrow button at the 
lower right of the window). 

Expected results:
The previews/thumbnails should change when the image's contents change (even 
if it's simply the color palette entries changing, not the actual pixels). 

Does this happen every time?
Yes 

Other information: