08-09-2016 12:09 PM - edited 08-09-2016 03:50 PM
... by accepting and installing the new Windows 10 Home update to Version 1607!
Don't know why, but Microsoft fixed something in graphics that allows instant, proper switch back and forth between the built-in display and my external display. And, as a bonus, the external desktop even looks just like the built-in - just bigger - with no monster icons!
My setup is:
Yoga 900-131SK (Win 10 Home x64 - 16 GB - 512 GB - All Lenovo S/W updated installed)
Sceptre XG22 (w/ DVI to HDMI cable)
Cable Matters USC-C Multiport Adapter w/ Ethernet (linked to my 900 with a 3' USB-C extension cable - <$15 from Amazon.com)
Plugable 7-Port USB 3.0 Hub
Microsoft Sculpt Comfort Mouse - Bluetooth
Targus ADB33USX Keyboard - Bluetooth
New Version 1607 worked for me. I recommend it!