Version:           2.4.0 (using KDE 4.7.3) 
OS:                Linux

When switching from "preview mode" to "full-screen preview mode", the toggle button for "Show Thumbbar" is in an invalid state:

Thumbbar is not visible, but Button is enabled.

Reproducible: Always

Steps to Reproduce:
1. start digikam
2. select album with picture
 -> thumbnail-view (no thumbnail-bar on top)

3. doubleclick/ENTER
 -> switch from "thumbnail view" to "image preview"
    (thumbnail-bar visible on top)

4. hit CTRL + SHIFT + F
 -> full screen view, but no thumbnail-bar visible on top

5. now try to enable the thumbnail-bar


Actual Results:  
If I want to see the thumbnail-bar in full-screen-preview, I have to hit CTRL + T __twice__. (CTRL + T is the shortcut for "Show Thumbbar")

Expected Results:  
If I don't see the thumbnail-bar, I have to hit CTRL + T only once, to toggle the thumbnail-bar-view-switch "on".

Tip: Add the "Show Thumbbar"-Button to your digiKam toolbar, to see the inconsistent states.