# trackMouse(with:in:of:untilMouseUp:) Handles a mouse-down event on the cell’s image, and optionally waits until a mouse-up event ``` @MainActor func trackMouse(with theEvent: NSEvent, in cellFrame: NSRect, of controlView: NSView?, untilMouseUp flag: Bool) -> Bool ``` ## Parameters `theEvent` The mouse-down event. `cellFrame` The region of an [`NSTextView`](/documentation/AppKit/NSTextView) in which to track further mouse events. `controlView` The view that received the event. Typically, this view is an [`NSTextView`](/documentation/AppKit/NSTextView) object and is focused. `flag` A Boolean value that indicates whether to track the mouse until a mouse-up event occurs. If this parameter is , stop tracking when a mouse-dragged event occurs outside of `cellFrame`. ## Return Value if the cell successfully finished tracking the mouse, or if tracking was unsuccessful. ## Discussion The [`NSTextAttachmentCell`](/documentation/AppKit/NSTextAttachmentCell-swift.class) implementation of this method calls upon `aTextView`’s delegate to handle the event. If `theEvent` is a mouse-up event for a double click, the text attachment cell calls the [`textView(_:doubleClickedOn:in:at:)`](/documentation/AppKit/NSTextViewDelegate/textView(_:doubleClickedOn:in:at:)) method of its delegate and returns . Otherwise, depending on whether the user clicks or drags the cell, it sends the delegate a [`textView(_:clickedOn:in:at:)`](/documentation/AppKit/NSTextViewDelegate/textView(_:clickedOn:in:at:)): or a [`textView(_:draggedCell:in:event:at:)`](/documentation/AppKit/NSTextViewDelegate/textView(_:draggedCell:in:event:at:)) message and returns . The [`NSTextAttachmentCell`](/documentation/AppKit/NSTextAttachmentCell-swift.class) implementation returns only if `flag` is and the mouse is dragged outside of `cellFrame`. The delegate methods are invoked only if the delegate responds. ## See Also [`trackMouse(with:in:of:untilMouseUp:)`](/documentation/AppKit/NSCell/trackMouse(with:in:of:untilMouseUp:)) Initiates the mouse tracking behavior in a cell. [`lockFocus()`](/documentation/AppKit/NSView/lockFocus()) Locks the focus on the view, so subsequent commands take effect in the view’s window and coordinate system. --- 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)