And so one day, I set to build a lightweight desktop environment around lxde. After some customizations, the thing that bugged me was that I could not set the keyboard layout change shortcut to the Win + Space shortcut that I have grown to like. What's not to like about it. I found it brilliant when I discovered it in OS X and was delighted to discover that it became the default in Windows 10. So I have standardized to that and not being able to configure it in lxde is a huge bummer for me.
It turns out that by default the lxpanel xkbd switching applet does not allow you to choose Win+Space as a layout switching shortcut. But fear not. You can just add it by adding the line:
grp:win_space_toggle=Win+Space
Just edit the toggle.cfg file
sudo vim /usr/share/lxpanel/xkeyboardconfig/toggle.cfg
And you are done.
You can see all the possible options supported by your X server in
man xkeyboard-config
If you are more of a barebones type, you can more or less achieve the same effect temporarily by using setxkbmap.
setxkbmap us,gr -option 'grp:win_space_toggle'
but this does not persist after the current X session ends.
setxkbmap -print
Prints the current settings.
The freebsd handbook provides some good examples to set a system-wide default.
I guess a configuration for my case, that I have not tested yet, would be putting something like the following:
Section "InputDevice"
Identifier "Keyboard1"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "us,gr"
Option "XKbOptions" "grp:win_space_toggle"
EndSection
Under /usr/local/etc/X11/xorg.conf.d/kbd-layout-multi.conf
See also the more extensive XKB config docs