I have written a small command line with autocomplete. Neither finished nor beautiful yet, but working for me. Maybe someone is bored and very good in CSS and jQuery.

It can be found here:
https://github.com/thetumbledtype/moi3d-scripts-other/blob/master/CmdLine.htm

Great!
But I think it will be better to read all commands directly from the commands directory.
Try this:

cmds=[];
var files = moi.filesystem.getFiles(moi.filesystem.getCommandsDir(), '*.js' );
for ( var i = 0; i < files.length; i++ ) { cmds.push( files.item(i).substring(files.item(i).lastIndexOf(moi.filesystem.getPathDelimiter())+1, files.item(i).lastIndexOf("."))); }	

I have removed the icons from sidepane.htm so that I have more space for objects, since I tend to have several layers for construction lines and profiles. Right now it works for me, but I have to work with it for a while to see whether there better possibilities for me to choose tools.

What really didn't work was making the whole thing part of a fly out menu, because the resizing closes the window. Otherwise I would have written something that just adds a search field to ExtScriptsFull.menu.htm.

Hi Max, found out your example is not working when running MoI using Wine. moi.filesystem.getPathDelimiter() for some reason returns Ubuntu's / and not Wine's \.

var cmds = [];
var files = moi.filesystem.getFiles(moi.filesystem.getCommandsDir(), '*.js');
for ( var i = 0; i < files.length; i++ ) {
    var fn = moi.filesystem.getFileNameFromPath(files.item(i));
    cmds.push(fn.slice(0, -3));
}
cmds.sort();