The Select actions are enabled when the caret is positioned inside a tag name.
+ → : Selects the entire current element;
+ → : Selects the content of the current element, excluding the start tag and end tag. If it is applied repeatedly starts with selecting the XML element from the cursor position and extends the selection to the ancestor XML elements. Each execution of the action extends the current selection to the surrounding element;
+ → : Selects all the attributes of the current element;
+ → : Selects the parent element of the current element;
Double click on an element or processing instruction - If the double click is done before the start tag of an element or after the end tag of an element then all the element is selected by the double click action. If it is done after the start tag or before the end tag then only the element content without the start tag and end tag is selected.
Double click after the opening quote or before the closing quote of an attribute value - select the whole attribute value.