Using Mac download on my computer. This has been a nuisance for a couple of years. I cannot predict when it will work and when it will close out a form. For example, in a charitable contribution form, I can fill in the name of the organization and tab to the address fields and through them. Later in the form, if I click Tab and there is no field to jump to, the form closes. Instead of closing the form, an invalid Tab command should be null. I think it's a fixable bug. Thanks for responding.