Ubuntu – Setting Workspaces in Gnome without activating gnome panel (and workspaces applet)

You'll need to start the network manager applet. It's started by default, although it sounds like you've done some customisation. Here's a screenshot of my entry :

This is available through system/preferences/startup applications.

I've finally managed to resolve spacing problem and ready to share my solution. Add to ~/.config/gtk-3.0/gtk.css following lines:

.gnome-panel-menu-bar.menubar .menuitem,
PanelWidget .button {
    padding: 0px 4px;
}

First line affects spacing of the menu headers (Applications and Places), second one affects launchers spacing. Here is the result:

You can increase spacing even more, changing second padding parameter (6 pixel will make it even with the spacing of the Indicator Applet icons in the top right corner), but I'm pretty happy with 4 pixel. Remember that increasing of padding will also make task buttons on the bottom panel wider, as they are also Panel Widgets. Or you can set spacing separately for the menu headers and launchers - it's up to you:

.gnome-panel-menu-bar.menubar .menuitem {
    padding: 0px 4px;
}

PanelWidget .button {
    padding: 0px 3px;
}

Update: Finally found the way to increase panel separators padding. Add to ~/.config/gtk-3.0/gtk.css several more lines:

PanelSeparator {
    padding: 4px 8px;
}

First padding parameter will reduce the length of separators, second one will make the spacing on both sides of the separator. Here is the final result: