I noticed this after adding some custom toolbar buttons (here: Permission overview, Request talk power and Grant talk power), when using multiple servers.

On server A, I have the permissions to see the permission overview and to grant talk power, so both buttons are always activated - nevertheless what I select; so for example a channel, or a user that already has talk power (and which grant would result in an error then).

On server B, I can only request talk power, so only that button is activated.

Now when I am connected to both servers and say, the button statuses from server A are active and I then switch to server B, nothing changes in the toolbar. This basically means that I am still able to press permission overview (in which case I would get the permission overview of the last selected user on server A), and I can still press the grant permission button (while getting errors on server A).
If I modify the toolbar while having server B activated, the buttons refresh, so I have the correct buttons for server B; but then again they don't change when switching to server A.

So basically, the buttons never refresh. But they should refresh, whenever the selection or the active server changes.