I use Proclaim on OSX. I'm losing my eyesight and find myself depending increasingly on VoiceOver. Unfortunately, Proclaim doesn't appear to be compatible with VoiceOver, or, at best, isn't well-tested with VoiceOver enabled. Many controls are difficult or impossible to access using VoiceOver. I can provide specifics if desired.
As it turns out, in my day job, I'm a computer programmer. From what I know about developing software for OSC, my understanding is that most Apple controls work "out of the box" with VoiceOver, and breakages occur primarily when software developers try to do all sorts of customizations to the controls. These customizations in and of themselves are not bad, but if they are made without any kind of VoiceOver testing in the QA process, the result is that the customizations are incompatible with VoiceOver. This is my guess as to why Proclaim is so difficult to use with VoiceOver: Lots of customizations to the on-screen controls, and probably zero testing with VoiceOver enabled. If this is true, the simple solution would be for you all to change your custom controls over to stock controls.
If you lack the in-house resources and are looking for expertise on VoiceOver development and testing, I can probably point you to some resources that might help you out. Also, I'd be willing to be a beta tester for any changes aimed at increasing VoiceOver compatibility, and I'd gladly do that free of charge.
Please consider making these improvements for those of us who suffer from visual impairments. Thanks.
