System/Preferences/KeyboardShortcuts there is a shortcut key called
Mod4+D that can be used to minimize windows. How is
Mod4+D entered on a keyboard and what is the meaning of the Mod4?
You can see what keys are bound to which modifiers using the
xmodmap tool. For example:
$ xmodmap xmodmap: up to 4 keys per modifier, (keycodes in parentheses): shift Shift_L (0x32), Shift_R (0x3e) lock Caps_Lock (0x42) control Control_L (0x25), Control_R (0x69) mod1 Alt_L (0x40), Alt_R (0x6c), Meta_L (0xcd) mod2 Num_Lock (0x4d) mod3 mod4 Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf) mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)
Super_R keysyms correspond to the Win keys on your keyboard.