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Always Show a Tooltip with Carbon or Cocoa

I had the following problem on the Mac: in certain circumstances I want to always display a tooltip and change the text of the tooltip as the mouse moves over different objects. So I looked around and I found the Carbon Help Manager Reference.

The functions HMDisplayTag() and HMHideTag() seemed to be exactly what I was looking for. Implementing this was rather straightforward and it worked most of the time. But sometimes it simply stopped working; after some debugging I found out that after the call of HMHideTag(), I did not get any mouse moved events anymore.

So I looked around for other solutions and found the tooltip article on CocoaDev. That one looked really promising. It has two different approaches of implementing your own tooltips with Cocoa. But since they simply display a window with a style that resembles tooltips, I continued looking (after all, if I use Apple’s tooltip API, I am more likely to get a correct look of the tooltips, especially if Apple decides to change the look of tooltips at some point).

But on CocoaDev there is also an article that shows a different approach: it uses the Cocoa NSHelpManager class to do this job.

This code simply uses the showContextHelpForObject:locationHint: function to show the tooltip and the removeContextHelpForObject: to hide the tooltip. Happy to have a found another solution, I tried this and showing the tooltip worked just find. But to my disappointment, I was not able to get rid of the tooltip anymore — the removeContextHelpForObject: did in fact not hide it. I tried several different ways, but with no luck.

So to cut a long story short, I ended up with using HMDisplayTag() again to show the tooltip. And since the HMHideTag() call was the only thing that caused me trouble, I simply replaced it with:

    WindowRef helpTagWindow = GetFrontWindowOfClass(kHelpWindowClass, true);
    if (helpTagWindow)

As far as I can tell, this works just fine for me. So I will stick to this unless I discover any mayor problems.

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