[1] Yes, one can use Qt for commercial software without buying a license (as long as it is dynamically linked), but their marketing does everything it can to hide that fact. Also, the newer additions to Qt do not fall in this category – for those, you have to pay.
Here are the most commonly used options:
- Go LGPL. Sure, you will need to ship binaries and libs, but there are tools within the SDK that do this automatically for you (windeployqt, macdeployqt, etc.). And as others have stated, it is a problem that was solved years ago.
- Go Commercial to link statically. If you are a single developer, there is an annual license available for $499 (up to $100k yearly revenue).
It might not be worth the price, but that is hardly ridiculous. It is quite believable to get a 4% productivity improvement from appropriate tooling. You need to do a cost-benefit analysis to determine the answer to that question.
If you're doing a GUI, you have no reason to be doing canvas manually.
I think less than 1% of the users use it on mobile, but it's designed as a mobile interface.
To scroll you need to click and drag, or you need to click 5px buttons. Regular mouse scroll doesn't work.