I claim the ornamental design for a display screen, or portion thereof, with a graphical user interface, as shown and described.
FIG. 1 is the first image in a sequence for a display screen, or portion thereof, with a graphical user interface showing a first embodiment of the new design;
FIG. 2 is a second image thereof;
FIG. 3 is the first image in a sequence for a display screen, or portion thereof, with a graphical user interface showing a second embodiment of the new design;
FIG. 4 is a second image thereof;
FIG. 5 is the first image in a sequence for a display screen, or portion thereof, with a graphical user interface showing a third embodiment of the new design; and,
FIG. 6 is a second image thereof.
The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-2; FIGS. 3-4; and FIGS. 5-6. The process or period in which one image transitions to another forms no part of the claimed design. The broken lines in the drawings illustrate portions of the graphical user interface that form no part of the claimed design.