The ornamental design for a displayscreen or portion thereof with a graphicaluserinterface, as shown and described.
FIG. 1 is a front view of the first image of a display screen or portion thereof with a transitional graphical user interface showing the new design.
FIG. 2 is a front view of the second image of the display screen or portion thereof with a transitional graphical user interface showing the new design.
FIG. 3 is a front view of the third image of the display screen or portion thereof with a transitional graphical user interface showing the new design.
FIG. 4 is a front view of the fourth image of the display screen or portion thereof with a transitional graphical user interface showing the new design.
FIG. 5 is a front view of the fifth image of the display screen or portion thereof with a transitional graphical user interface showing the new design.
FIG. 6 is a front view of the sixth image of the display screen or portion thereof with a transitional graphical user interface showing the new design; and,
FIG. 7 is a front view of the seventh image of the display screen or portion thereof with a transitional graphical user interface showing the new design.
The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-7. The process or period in which one image transitions to another forms no part of the claimed design. The broken lines represent the display screen or portion thereof, text, and graphic elements that form no part of the claimed design