Thank you for this feedback! I pushed an update to prss.co to prevent a new page from displaying when direct download is chosen.
Regarding the static_themes missing, you are correct.. I will submit a new store build for this one! Hopefully folks are not having issues that prevent them from loading the app, and not consistently.
On the topic of window state, the goal of dismissing the app to "Tray" is to lessen the perf hit of startup cycles, for example when the configuration is fetched (which contains the theme list, bought addons and so on) and to support the Autoblogger addon (which, when enabled by the user, can be configured to create posts at a schedule). I do send an OS notification right away (something to the effect of "PRSS is still running in Tray"), but I agree that the UX is not perfect yet. Based on your feedback I will explore better ways to support these scenarios. Thank you!
By the way, as you keep exploring the app. Please do continue to send your feedback on here or the email attached in my profile page. Feedback like yours is really appreciated, I generally get very vague feedback in Feedback forms. Thanks again.