The ornamental design for a displayscreen or portion thereof with a graphicaluserinterface, as shown and described.
FIG. 1 is a display screen or portion thereof with a graphical user interface;
FIG. 2 is an expanded view of the left-hand side of FIG. 1;
FIG. 3 is an expanded view of the right-hand side of FIG. 1;
FIG. 4 is a second embodiment of the display screen or portion thereof with a graphical user interface.
FIG. 5 is an expanded view of the left-hand side of FIG. 4; and,
FIG. 6 is an expanded view of the right-hand side of FIG. 4.
The outermost broken line rectangle in FIG. 1 and FIG. 4 shows the display screen, and forms no part of the claims design. The vertical dash-dot-dot line styles in FIGS. 2, 3, 5, and 6 denote sectional views. All other broken lines are features of the graphical user interface that form no part of the claimed design.