raise {plot_window_nb}
The raise command raises (opposite to lower) plot window(s) associated with the interactive terminal of your gnuplot session, i.e. pm, win, wxt or x11. It puts the plot window to front (top) in the z-order windows stack of the window manager of your desktop.
As x11 and wxt support multiple plot windows, then by default they raise these windows in descending order of most recently created on top to the least recently created on bottom. If a plot number is supplied as an optional parameter, only the associated plot window will be raised if it exists.
The optional parameter is ignored for single plot-windows terminal, i.e. pm and win.
If the window is not raised under X11, then (1) they don't run in the same X11 session (telnet or ssh session, for example), or (2) raising is blocked by your window manager. On KDE, you may like to go to the KDE Control Center => Desktop => Window Behaviour => Advanced and set the "Focus stealing prevention level" to None (default is Low).