The ornamental design for a retractable supportmechanism for an electronic device, as shown and described.
FIG. 1 is a perspective view illustrating a retractable support mechanism for an electronic device;
FIG. 2 is a back elevation view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view thereof, shown in a retracted position.
The broken lines illustrating the monitor, keyboard, touchpad and laptop portion in FIG. 1 illustrate environment that forms no part of the claimed design, while the remaining broken lines in FIG. 1 illustrate portions of the retractable support mechanism for an electronic device that form no part of the claimed design. The broken lines shown in FIGS. 2-7 illustrate the environment of the claimed design and form no part thereof.