BINGO!!! I happened to have some Velcro tape that comes with very powerful adhesive. Velcro works because there are two types of surfaces involved. Paraphrasing Wikipedia, the word Velcro is a Portmanteau of two French words:
- Velour ("velvet"), LOOPS - A mat of tiny hair-like loops that feel smooth to the touch, and
- Crochet ("hook"), HOOKS - Tiny plastic hooks that feel rough to the touch.
There is a strong visual cue if you use light-colored Velcro tape on black connectors, and dark-colored Velcro tape on white connectors. However, even if (as the second photo shows) the connector and the Velcro tape are white, you can generally see the glint of the rough texture of the Velcro HOOKs. Of course, Velcro comes in white and black and and other colors so you have your choice.
As the fourth photo indicates, you can paste a strip of the Velcro LOOP tape onto the surface of your charger, so you can easily wrap the cord and secure the connector. I'm sure you will find interesting places to paste the Velcro LOOP material to hold your Velcro HOOK material connectors.
I hope manufacturers of flat connectors will catch onto this idea and include Velcro HOOK pads on their products.
AND, ONE MORE THING
Here is a great idea* I offer free to any manufacturer who may wish to use it.
Manufacturers could design an Adapter Tip for Cellphone, Tablet, HDMI, and USB connectors with both a Velcro HOOK pad and a micro-light, and sell them for a couple dollars each.
When you plug your connector into the Adapter Tip, the micro-light will confirm that the connector is "live" (that is, the charger or PC or other device attached to the connector is on and working) . In addition, the tiny spot-light will help you locate the socket. After the Adapter Tip is connected to your device, it could be designed to extinguish the micro-light, which will confirm that it is plugged in securely. Alternatively, there could be a micro-switch to turn the light on when desired.
Of course, the best implementation of this idea would be if manufacturers included both the Velcro pad and a micro-light on all connectors for all new devices.
*I did a Google on "lighted connector" but could only find power cords with a light feature. Furthermore, the lights appeared to be designed to indicate that the power cord was "live" and not to help the user find the socket and plug it in.