Display panel or portion thereof with a transitional graphical user interface

FIG. 1 is a front view of a display panel or portion thereof with a graphical user interface showing a first image in a sequence of our design;

FIG. 2 is a front view of a display panel or portion thereof with a graphical user interface showing a second image in the sequence of the design;

FIG. 3 is a front view of a display panel or portion thereof with a graphical user interface showing a third image in the sequence of the design;

FIG. 4 is a front view of a display panel or portion thereof with a graphical user interface showing a fourth image in the sequence of the design; and,

FIG. 5 is a front view of a display panel or portion thereof with a graphical user interface showing a fifth image in the sequence of the design.

The subject matter of the present disclosure includes a process or period during which one image transitions into another. The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-5 . The process or period in which one image transitions to another image forms no part of the claimed design.

The broken lines depicting a display panel or portion thereof are included for the purpose of illustrating environmental structure and form no part of the claimed design. The broken lines depicting portions of a graphical user interface are included for illustrating environmental aspects of a display panel or portion thereof with a transitional graphical user interface and form no part of the claimed design.