The ornamental design for a displayscreen or a portion thereof with a transitionalgraphicaluserinterface, as shown and described.
FIG. 1 is a front view of a display screen or a portion thereof with a transitional graphical user interface; and,
FIG. 2 is a front view of a display screen or a portion thereof with a graphical user interface transitioned in sequence from FIG. 1.
The outer broken-line rectangle shows a display screen or a portion thereof forms no part of the claimed design. The broken-line text and numbers illustrate portions of a graphical user interface and form no part of the claimed design. The areas shown in black tone illustrate a contrast of appearance.
The appearance of the animated graphical interface sequentially transitions from FIG. 1 to FIG. 2. The process or period in which one image transition to another image forms no part of the claimed design.