how to navigate system dialogue boxes never touching the mouse? I often open files, mess with them and then close them, not wanting to save. The system dialogue prompt always asks me if I want to save and this is annoying. I want this nag to end as quickly as possible, but my keyboard arrows won't change highlighted field (I's on cancel by default). Tab is ok, but still too slow. How do I 
A: quit a close a document (without saving) without touching the mouse?
or 
B: disable the "do you want to save" dialogue completely without touching the mouse? 

A fix for either scenario would make my life more streamlined.
If you've got one of the standard macOS file save sheets, such as:


  Do you want to save the changes you made in the document ‘untitled’?
  Don't Save | Cancel | Save



↩︎ enter will save.
⎋ esc will cancel.
⌘⌫ command-backspace will not save (usual Finder delete shortcut).


If the sheet is a slightly different macOS file save sheets, where the document has not been saved previously, then ⌘⌫ will select the Delete button from the options


  Delete | Cancel | Save


For macOS file save sheets which prompt for a destination to save the file, you can quickly jump to a standard folder using the following shortcuts:


⇧⌘O for ~/Documents
⌘D or ⇧⌘D for ~/Desktop
⇧⌘H for ~ (your home folder)
⌥⌘L for ~/Downloads
⇧⌘I for iCloud Drive
⇧⌘G or / or ~ to enter a path name by typing the path


Some of these shortcuts are described in the Apple KB article Mac keyboard shortcuts

The ‘don't save’ shortcut used to be ⌘D, however many save sheets have an option to specify the location for the document, in cases where the location is undefined. ⌘D chooses the Desktop for the destination. To revert macOS back to ⌘D for ‘don't save’, set the following key:

defaults write -g NSSavePanelStandardDesktopShortcutOnly -bool true