The ornamental design for a displaypanel with a transitional graphical user interface, as shown and described.
FIG. 1 is a front view of a display panel with a transitional graphical user interface showing a first image in the sequence showing my new design;
FIG. 2 is a front view of a second image thereof;
FIG. 3 is a front view of a third image thereof;
FIG. 4 is a front view of a fourth image thereof;
FIG. 5 is a front view of a fifth image thereof;
FIG. 6 is a front view of a sixth image thereof;
FIG. 7 is a front view of a seventh image thereof;
FIG. 8 is a front view of a eighth image thereof; and,
FIG. 9 is a front view of a ninth image thereof.
The broken lines around the Figures show a display panel or portion thereof, and form no part of the claimed design.
The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-9. The process or period in which one image transitions to another image forms no part of the claimed design.