Priorities and help requested (not applicable if asking question):

Are you willing to submit a PR to fix? Yes

Requested priority: Normal

Products/sites affected: Normal

Describe the issue:

The dismiss button for single line MessageBars that have actions is in an odd/unintuitive place. On Windows and Office, the dismiss button is on the outer edge, to help with Fitt's Law.

Actual behavior:

On left to right the order is:

(Icon) Message               X  [Action]

Expected behavior:

(Icon) Message              [Action]  X