Some shortcomings when it comes to the new appointment vote feature in calendar

Is your feature request related to a problem? Please describe.

I really like the new appointment vote/proposal feature. However, I've encountered a few shortcomings or design flaws while using it.

1. I can't select the calendar where the appointment is created after picking one of the proposed dates. It's always my personal calendar. I have to change the appointment by hand afterwards, which is annoying.
2. If I define a date by holding mouse and dragging it downwards, I get an error for not setting a time after releasing the mouse button. To make it work I have to click one of the timeframes on the left. I think this is a bug.
3. Showing the free time in the calendar by a crosshatched area is a confusing since usually unavailable timeframes are shown as a solid element in the calendar view. This is the opposite.

But still, great new feature. Keep it up 👍

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Describe alternatives you've considered

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Additional context

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Reproduce the appointment vote/proposal flow in the calendar UI, covering selecting a proposed date, dragging to define a date, and the crosshatched free-time display. Start by tracing the frontend entry points for this feature; done means the target calendar can be chosen, dragging does not fail without a separate timeframe click, and availability styling is unambiguous.