For `Control` + `left mouse button` case, we probably doesn't handle the mouse event which is generated from widget code, https://searchfox.org/mozilla-central/rev/a4be2fbe9bd4f405c91cc16e4e3a80400f5a9301/widget/cocoa/nsChildView.mm#3618-3625, well.
Bug 1504210 Comment 6 Edit History
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We probably doesn't handle the mouse event with modifiers well.