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 display screen or portion thereof with transitional graphical user interface showing the first image in a sequence;
FIG. 2 is a front view of the second image included in the sequence; and,
FIG. 3 is a front view of the third image included in the sequence.
The longer-incremented broken lines showing of a portion of a display screen of a communications terminal illustrate environment and form no part of the claimed design. The medium length broken lines show a border of the claimed design. The images and text shown in finer-incremented broken lines illustrate features that form no part of the claimed design.
The greyscale in the drawings indicates a contrast of appearance.
The subject matter in this patent includes a process or period in which an image changes into another image. The process or period in which an image transitions to another image forms no part of the claimed design.