Heal & Clone Tool

[rich2005]

I believe the ctrl key equivalent in a Mac is the 'command' key.

This from another source, might be worth a try

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>- Go to "System Settings"
>- Select "Mouse and Touchpad"
>- UNCHECK the box "Show position of pointer when the Control key is
>pressed"
>
>Then restart GIMP
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Otherwise have you any other software that uses that particular key sequence (ctrl)/command - leftclick