src/vs/workbench/contrib/mergeEditor/browser/view/mergeEditor.ts/MergeEditor/computeEditorViewState
class MergeEditor:	protected computeEditorViewState(resource: URI): IMergeEditorViewState | undefined {
		if (!isEqual(this.model?.result.uri, resource)) {
			// TODO@bpasero Why not check `input#resource` and don't ask me for "forgein" resources?
			return undefined;
		}
		const result = this.inputResultView.editor.saveViewState();
		if (!result) {
			return undefined;
		}
		const input1State = this.input1View.editor.saveViewState() ?? undefined;
		const input2State = this.input2View.editor.saveViewState() ?? undefined;
		const focusIndex = [this.input1View.editor, this.input2View.editor, this.inputResultView.editor].findIndex(editor => editor.hasWidgetFocus());
		return { ...result, input1State, input2State, focusIndex };
	}