Thank you for your post.
I am unable to replicate the issue using FileMaker Pro 14.0.1 on my iMac running Mac OS X 10.10.3. This is what I have done.
1. I created a button named "No" that is set to "Do Nothing"
2. I created a button named "Yes" that is set to Single Step -> Show Custom Dialog [ "YES" ; "YES ], and checked the option "Change cursor to hand over button".
3. I created a Text field "Checkbox", formatted it as a Checkbox set that includes a value set of "Yes".
4. I selected the "No" button, and in Inspector -> Data -> Hide object when, I set the formula to: IsEmpty ( Checkbox )
5. I selected the "Yes" button, and in Inspector -> Data -> Hide object when, I set the formula to: Checkbox = "Yes"
6. I placed the "No" button on top of the "Yes" button.
7. In Browser mode, I see the No button. I can put my cursor on the button, it remains an arrow, and when I click it, nothing happens.
8. I enter a checkmark in the "Checkbox" field, and now the "Yes" button shows. When I hover over the button, the cursor changes to a hand, and when I click the button, the dialog box appears with "YES" appearing.
9. I continually checked and unchecked the "Checkbox" field, and I could not get the results you encountered. Every time, the hand cursor would appear automatically when I hovered over the "Yes" button, and no hand cursor over the "No" button.
Let me know what I am doing differently than you so I can replicate the issue.