Do not leave an editor behind when the unified diff falls back - #2853
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vogella merged 1 commit intoAug 7, 2026
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Opening the unified diff opens the text editor first and only then finds out whether the diff can be applied at all: the editor registered for the file may not be a text editor, or applying the diff may fail. In those cases the classic compare editor takes over, but the editor opened a moment earlier stayed open, so the user ended up with two editors on the same file, one of them without any comparison in it. That is what happens for file types whose default editor is not a text editor. An editor opened by this code is now closed again before falling back. One that was already open is left alone, and it is recognized by comparing the part openEditor returns with the one found beforehand, rather than by asking twice whether an editor exists. On the fallback path the editor briefly becomes visible before it closes again. Avoiding that would mean knowing the part type without opening it.
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Opening the unified diff opens the text editor first and only then finds out whether the diff can be applied at all: the editor registered for the file may not be a text editor, or applying the diff may fail. In those cases the classic compare editor takes over, but the editor opened a moment earlier stayed open, so the user ended up with two editors on the same file, one of them without any comparison in it.
An editor opened by this code is now closed again before falling back, while one that was already open is left alone. The two are told apart by comparing the part
openEditorreturns with the one found beforehand, rather than by asking twice whether an editor exists. On the fallback path the editor briefly becomes visible before it closes again; avoiding that would mean knowing the part type without opening it.The regression test registers a deliberately non-text editor for a test-only file extension, so the fallback is reproducible without depending on which editors happen to be in the target platform. A second test covers the other direction, that an editor the user already had open survives.
Contributes to #2795