Prevent multiple event attachments for mousemove in SelectionPlugin

[BryanValverdeU]

This PR ensures only one mousemove handler is attached when dragging selections and adds tests to verify this behavior.

• Added a guard in SelectionPlugin to prevent multiple mousemove attachments
• Updated tests to cover duplicate mouseDown calls and assert single attachment

[Copilot]

Pull Request Overview

This PR ensures only one mousemove handler is attached when dragging selections and adds tests to verify this behavior.

• Added a guard in SelectionPlugin to prevent multiple mousemove attachments
• Updated tests to cover duplicate mouseDown calls and assert single attachment

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/roosterjs-content-model-core/lib/corePlugin/selection/SelectionPlugin.ts	Prevent duplicate mousemove event attachments by checking mouseDisposer
packages/roosterjs-content-model-core/test/corePlugin/selection/SelectionPluginTest.ts	Add tests to simulate repeated mouseDown and assert only one attachment

Comments suppressed due to low confidence (4)

packages/roosterjs-content-model-core/lib/corePlugin/selection/SelectionPlugin.ts:222

• [nitpick] For clarity and consistency with the test's mouseMoveDisposer, consider renaming mouseDisposer to mouseMoveDisposer.

if (!this.state.mouseDisposer) {

packages/roosterjs-content-model-core/test/corePlugin/selection/SelectionPluginTest.ts:898

• Consider spying on editor.attachDomEvent here and asserting toHaveBeenCalledTimes(1) to explicitly verify that duplicate mouseDown events do not attach additional handlers.

expect(mouseDispatcher).toBeDefined();

packages/roosterjs-content-model-core/lib/corePlugin/selection/SelectionPlugin.ts:221

• [nitpick] Add a brief comment above the guard to explain that this prevents multiple mousemove attachments when a second mouseDown occurs before mouseUp.

//

packages/roosterjs-content-model-core/lib/corePlugin/selection/SelectionPlugin.ts:230

• This closing brace may prematurely end the onPluginEvent method. Verify that the if (!this.state.mouseDisposer) check and its corresponding logic remain inside the intended mouseDown handling block.

    }

[JiuqingSong]

how about we just dispose the previous one and then attach a new one? I'm afraid if in a corner case this may cause the event can never be attached.

[BryanValverdeU]

That works for me, changed in latest commit.