Emacs will only use the TAB character while indenting when indent-use-tab is 1.
Emacs can operate in two different input modes, traditional and GUI.
In GUI mode Emacs operates the highlight region in the style of Windows and Motif, a more intuitive mode.
The region will be set if you move the cursor while holding the shift key.
Typing or otherwise inserting text while the region is set will erase the region first. In effect replacing region with new text.
Using a delete command will erase the region rather then doing the normal delete action. delete commands includes, but is not limited to: delete-next-character, delete-next-word, delete-previous-character, delete-previous-word, erase-region.
Setting the mark manually, using the set-mark command, will temporarily disable the GUI input mode.
This constant is returned by the current-syntax-entity function when dot is located in a comment.
This constant is returned by the current-syntax-entity function when dot is located in punctuation or white-space.
This constant is returned by the current-syntax-entity function when dot is located just after a problem character.
This constant is returned by the current-syntax-entity function when dot is located just after a quote character.
This constant is returned by the current-syntax-entity function when dot is located in a matched quoted string.
This constant is returned by the current-syntax-entity function when dot is located in a word.