How to enable eyedropper color sampling with gesture while in mixer brush?

[Lunatique]

For some reason, when working in Artstudio Pro, I can only use eyedropper via gesture (I set it to one-finger prolonged touch) when in normal brush mode, but when in mixer brush mode, it will not work and I 'll have to tap on the eyedropper tool icon to use the eyedropper. Is this on purpose? But I can't think of why it would be designed that way on purpose.

[Lunatique]

For some reason, when working in Artstudio Pro, I can only use eyedropper via gesture (I set it to one-finger prolonged touch) when in normal brush mode, but when in mixer brush mode, it will not work and I 'll have to tap on the eyedropper tool icon to use the eyedropper. Is this on purpose? But I can't think of why it would be designed that way on purpose.

Sorry, there was a typo in the original post. It's supposed to read: "For some reason, when working in Artstudio Pro, I can only use eyedropper via gesture..."