Drag File onto Running App in Dock only works if doing it quickly

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Drag File onto Running App in Dock only works if doing it quickly

If I drag a file onto app in the dock, say a PDF in Preview when Acrobat is the default, or an .eml into Outlook when Mail is the default, I used to the able to drag and drop a file onto the app I wanted to open it and it would open it (if it could handle the filetype that is). Now, if the app is already running and I hold it over the app icon too long (more than a second or two) the app gets "focus" (I'm sure there's an Apple-y name for this, but it basically pushes everything else out of view an highlights any open window in the app in blue and maybe shows some other file icons at the bottom of the screen.

This would be fine except once this happens, the drop part of drag & drop no longer works. Dropping the file does nothing. If I do it quickly, it works, if I do it onto the app itself (in /Applications, not in the Dock) it works.

What is this blue highlighting about; what is it's purpose and how to I remove this functionality or at the very least make the time I have to release the file icon longer.

Thanks.

MacBook Pro 16″, macOS 15.4

Posted on Apr 27, 2025 6:27 AM

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Answer 1

Apr 27, 2025 8:54 AM in response to JSCooper

What you are seeing when you hover your file on a Dock icon is App Exposé in action.

It's a feature that allows you see all the open windows of an application. On a MacBook Pro, the default keystroke to invoke the feature is Ctrl-F3. The function key F3 alone, as indicated by its key cap, will invoke the Mission Control view of all open apps and their windows. As you move the cursor across any of these windows they will become framed in blue. Click the framed window and it will come front and center for you to work on.

View open windows and spaces in Mission Control on Mac - Apple Support (CA)

Why the drop-and-open function fails after that seems to be a minor bug. I can duplicate it on my MBA running Sequoia.

I have not taken the time to explore workarounds. Maybe others will contribute here. Until then, you may simply have to be more deliberate in your actions involving the Dock.

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Answer 2

Apr 27, 2025 7:03 AM in response to JSCooper

JSCooper wrote:

If I drag a file onto app in the dock, say a PDF in Preview when Acrobat is the default, or an .eml into Outlook when Mail is the default, I used to the able to drag and drop a file onto the app I wanted to open it and it would open it

basically pushes everything else out of view an highlights any open window in the app in blue and maybe shows some other file icons at the bottom of the screen.

What is this blue highlighting about;

Sounds like you turned on some Accessibility feature...

poke around there >System Settings>Accessibility

To trouble shoot further you can:

—A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies

Does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled temporarily.

Login and test. Reboot as normal and test. Caches get rebuilt automatically.

This test will tell you if third party interference; most extensions etc are not loaded in safe boot mode.

—Test issue in another user (or guest user) account Change Users & Groups settings on Mac - Apple Support

This will tell you if it a universal issue or isolated to your user/admin account.

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Answer 3

Apr 27, 2025 12:54 PM in response to JSCooper

If it is exposé as suggested above..

this is an often overlooked feature I use all the time from the trackpad; try making some change there to suit your needs.

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