Using the thunar 1.6.3 version, when I enter in a folder using detailed list mode view, it's only possible select several files in the same time with the mouse starting the selection from another item. When I click in a blank area to start the selection of multi itens the selection don't occours. This problem don't occurs using the icon view.
I can reproduce this bug for v 1.6.11. However it looks like for thunar-master the issue already got fixed ( possibly got fixed in package exo ) Will be released in thunar 1.8.0 ( development release 1.7.0, which has the fix is already available )