fix drag glitch when dragging across monitor boundary

[BillGoldenWater]

On macOS, when dragging across monitor boundary with a different scale factor, the QueuedEvent::ScaleFactorChanged event will be emit.

When process this event, will unconditionally set the content size, which would cause some glitch.

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Because the event is emitted with suggested_size set to current frame size.

So, if the user hasn't requested a size change, the call to setContentSize wouldn't actually change the size.

So, change to only call setContentSize if the user has requested a size change.

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• Tested on all platforms changed
• Added an entry to the changelog module if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality
• Updated feature matrix, if new features were added or implemented