STEPS TO REPRODUCE
Create a new project in Beta 28
In the text document, type “hello, world”
Double-click the word hello.
RESULT: the word itself and the preceding smartquote are selected.
Double-click the word world.
RESULT: the word itself and the trailing smartquote are selected.
NOTE: If the adjacent double quote is a regular non-smart quote, the selection works as expected. (i.e., only the word itself is highlighted).