GUI SpanPropertyForm: rm coupling of span and width (#856)

This resolves #856 (closed).

enabled an automatic merge when the pipeline for d15914d3 succeeds

aborted the automatic merge because source branch was updated

added 1 commit

• 4bb57a3c - clang-format

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enabled an automatic merge when the pipeline for 4bb57a3c succeeds

merged

mentioned in commit df2d870c