I use the Logitech Mouse MX with a Mac Mini computer that has the El Capitan OS X (version 10.11.5). To help configure the mouse, I have the Logitech Control Center (version 3.9.3) installed on the computer. I would like to configure the Left Button so that it will open folders and text files on the Computer Desktop with a double click. However, the default position for the Left Button is "Click." When I try to change the Left Button to Double Click, the following message appears: "Configuration Alert. You must assign at least one left click on this device. This button has been reassigned to a left click." Basically, I am trying to configure the Left Button so that it performs both click and double click functions, not just one function or the other. I experienced this dual functionality with the Left Button on the Mavericks OS X, but it no longer seems possible with the El Capitan OS X. Thanks for any tips on how to configure the Left Button so that it performs the click and double click functions on the Mac El Capitan OS X.