The ornamental design for a displayscreen or portion thereof with transitional graphical user interface, as shown and described.
FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;
FIG. 2 is a front view of a second image thereof; and,
FIG. 3 is a front view of a third image thereof.
The appearance of the transitional images sequentially transition between the images shown in FIGS. 1 through 3. The subject matter of this patent includes a process or period in which an image changes into another image. This process or period forms no part of the claimed design.
The broken line showing of a display screen or portion thereof with transitional graphical user interface is included for the purpose of illustrating portions of the article and forms no part of the claimed design.