Transcribed from Dmitri Popov's blog, 31 May 2011
The main toolbar in digiKam provides quick access to several tools and features, and you can tweak it to fit your particular photographic workflow. To do this, choose thecommand. This opens the dialog window where you can add, remove, and tweak toolbar buttons.
To add a new button to the toolbar, simply select the entry you want in the pane and drag it with the mouse to the desired position in the pane (you can also use the Arrow buttons for that). To arrange the available commands into logical groups, you can use the special entry. You don’t fancy the default icon of a specific button? Press the button and assign the button an alternative icon. And using the button, you can modify the default button label. That’s all there is to it.