* Tilda completion (~/ <==> $HOME/)
* Completion works for separate words (e.g. you can type em<TAB> which
  turns to emacs, type a SPACE, and write the file you want to open using
  completion).
* Configuration file: ~/.gmrunrc or /etc/gmrunrc.
  Check one of them, configuration is very simple. From that file you
  can change window position and width, history size, terminal, URL
  handlers, etc.
* CTRL-Enter runs the command in a terminal.
* CTRL-Enter without any command starts a new terminal.
* History is maintained in the file "~/.gmrun_history".
* CTRL-R to search backwards through history.
* CTRL-S to search forward through history.
* "!" enters a special search mode, matching only the start of strings.
-- Esc to cancel search (only once).
-- CTRL-G to cancel search and clear the text entry
* URL handlers allowing you to enter lines like "http://www.google.com"
  to start your favorite browser on www.google.com.
  The URL-s are configurable from the configuration file.
* Extension handlers.  Basically you can run, for instance,
  a ".txt" file, assuming that you have configured a handler for it
  in the configuration file.

    ./configure --prefix=/usr --sysconfdir=/etc
    make
    make install
By default it will use the GTK3 ui if it's available.
Pass `--enable-gtk2` to `./configure` to build the gtk2 ui
Optionally you can configure your window manager to call gmrun
with WinKey + R or something.