When I try to display web inspector just a grey background shows instead of that. I tried to restart browser but it didn't help. It happens in Safary 7 OS X Mavericks.
Anybody knows what is that could be?
A quick fix that brought the inspector back for me was to resize the web inspector pane by moving the mouse to the top edge until the pointer changed to the resizing pointer and dragging.
A reboot seems to solve the problem.
Solution (works permanent, without reboot):
killall -KILL Dock
This is Dock restart.
Also you can make alias in ~/.bashrc or ~/.bash_profile, for fast run of this cmd.
alias dockrestart="killall -KILL Dock"