# mouseDown(onCharacterIndex:coordinate:withModifier:continueTracking:client:) Handles mouse-down event send to an input method. ``` func mouseDown(onCharacterIndex index: Int, coordinate point: NSPoint, withModifier flags: Int, continueTracking keepTracking: UnsafeMutablePointer!, client sender: Any!) -> Bool ``` ## Parameters `index` The index within the sender’s text storage where the mouse-down event occurred. `point` The point at which the mouse-down event occurred. `flags` The modifier keys. `keepTracking` Set this parameter to if you want to receive subsequent mouse-moved and mouse -up events. `sender` The client object. ## Return Value if handled; otherwise . ## Discussion Implement this method if your input method handles mouse-down events. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)