There are a couple problems with the unindent (shift+tab) shortcut I have found.
The first problem happens when trying to unindent a single indented line. If you have the cursor at the beginning of the line, or you highlight only that line (neither of the newlines to either side), nothing happens when you press the unindent shortcut. If you highlight at least one character of the line above or below, then both lines will unindent, as expected. Expected behaviour: the single line should unindent if it is the only line selected.
The second problem is odd and happens only when translateTabsToSpaces is set to true. If you select multiple indented lines, where the selection begins at and is inclusive of column 1, and the line immediately above the selection is empty, pressing the unindent shortcut will unindent the selected block by tabSize x 1 spaces as expected, but the first line of the selection will be unindented by tabSize x 2. Here is a simple illustration:
// tabSize 2, translateTabsToSpaces true, the line below is empty
If you highlight the "hello world" lines, being sure to begin the selection at column 1 of the "hello" line (select the entire line), then press the unindent shortcut, the result is this:
[code]// tabSize 2, translateTabsToSpaces true, the line below is empty
If you begin the selection at column 2, or any higher column, or the line above the selection isn't empty, then all lines of the block will be unindented by tabSize x 1 as expected.