When designer selection changes are mirrored into split/code view, the same source range can be requested more than once around a designer content update. DocumentContainer now coalesces identical source-range selections before calling the active code view.
CodeViewMonaco also tracks the delayed native Monaco selection call. Pending identical selections are ignored, and pending delayed selections are cleared when the model is updated, so a selection queued against the old model is not applied after the refreshed model and followed by the same fresh selection.