The ornamental design for a displayscreen or portion thereof with a transitionalgraphicaluserinterface, as shown and described.
FIG. 1 is an enlarged front view of a first image in a sequence according to a first embodiment of my design for a display screen or portion thereof with a transitional graphical user interface; and
FIG. 2 is an enlarged front view of a second image in the sequence thereof.
FIG. 3 is a front view of a first image in a sequence according to a second embodiment of my design for a display screen or portion thereof with a transitional graphical user interface; and,
FIG. 4 is a front view of a second image in the sequence thereof.
The appearance of the transitional image transitions between the images shown in FIGS. 1-2 and 3-4. The process or period in which one image transitions to another forms no part of the claimed design.
The dash-dot-dash broken lines show portions of the graphical user interface and form no part of the claimed design. The dash-dash broken lines show a display screen or portion thereof and form no part of the claimed design.