The ornamental design for a displayscreen with a graphical user interface banner, as shown and described.
FIG. 1 shows a front views of a display screen with a graphical user interface banner according to a first embodiment of the claimed design.
FIG. 2 shows a front view of a display screen with a graphical user interface banner according to a second embodiment of the claimed design.
FIG. 3 shows a front view of a display screen with a graphical user interface banner according to a third embodiment of the claimed design.
FIG. 4 shows a front view of a display screen with a graphical user interface banner according to a fourth embodiment of the claimed design.
FIG. 5 shows a front view of a display screen with a graphical user interface banner according to a fifth embodiment of the claimed design; and,
FIG. 6 shows a front view of a display screen with a graphical user interface banner according to a sixth embodiment of the claimed design.
Broken lines in the FIGS. form no part of the claimed design. The broken lines on the outer perimeter of FIGS. 1-6 illustrate a portion of a display screen. The broken line text in FIGS. 1-6 illustrates portions of the graphical user interface that form no part of the claimed design. The broken black lines within the outer perimeter in FIGS. 5 and 6 illustrate the bounds of the claimed design and form no part thereof.