In my Win 7 64 bit, simply clicking in selected image in the film strip causes the image to be the most selected. Alt-click does the same thing. Control click deselects.
Also, one must be careful where one is pointing when clicking in the image. At the bottom of each thumbnail, there may be one or more icons. These indicate the existence of membership in a collection or keywords or a crop or develop adjustments. Clicking these causes an action depending on which you've clicked; a collection membership click opens a dialog with the names of the collections, clicking will take you to Library mode showing the collection, clicking on keywords opens Library mode with the keywords tab open, clicking on crop opens Develop mode with the crop tool open, clicking on adjustments opens Develop mode with Basic Adjustments tab open. These actions seem as if they might provide quite a shortcut!
Alan