#168 move the emulator settings to a tabbed sub-window

User Interface
Please move the emulator settings from the menu to a tabbed sub-window.

It is awkward to change several settings at once.  Right now it is like this,
when using a pointing device like for example a mouse, in these user interfaces
known to me (GTK/GNOME and XAW): Open the menu by moving the pointer to the
"Settings" menu in the main menu, select the desired setting from the menu or
sub menu by clicking the index finger mouse button and the menu closes. Now
this is fine if I would like to change only one setting, but this is too fiddly
when one wants to change several settings. I tried holding the shift and/or the
control and/or the alternate keys when clicking on the menu entry of a toggle
option, hoping the menu would not close so I could select another toggle
option, but the menu always closes itself.  If you think this perfectly makes
sense, you might be astonished by the way the menu behaves when invoked by the
keyboard (by pressing the key F10 in GTK/GNOME): The menu opens at the File
menu, good enough. Move to the Settings menu with cursors keys (3* right or 2*
left), move to a toggle option and toggle its value with the SPACE key, the
menu stays open (YES!!!) and one can select _a different_ menu item or close
the menu by pressing the F10 key again. To select/toggle only one menu item
press the ENTER key instead of the SPACE key and be done with it. Albeit this
is just marvelous and splendid and perfectly fine, I do not think it is
reasonable to think users would stop using these silly pointing devices - a
touch screen certainly is a pointing device, isn't it?