Please port the welcome screen back to widgets

It's time to accept the fact that no matter how hard we want to bring the convenience of QML on the desktop, Qt Quick is not a desktop toolkit. Qt Quick runs great in a single full-screen window. That means embedded Linux and mobile platforms. Using Qt Quick in a classic style desktop app with multiple resizable windows doesn't make much sense.

Let's look at some random screenshots on various platforms and configurations:

1. Scrolling welcome screen on OS X or Linux
   • Text rendering gets screwed when scrolling the Qt Quick based welcome screen.
2. Welcome screen gone black on Linux
   • Something somewhere probably called winId() so QQuickWidget went mad.
3. Resizing QQuickWindow on Windows
   • Can't reproduce this one wiht Qt Creator's welcome screen, but in general, resizing QQuickWindow on Windows is not pleasant.
   • The first impression is important. The first time you run an application, the window size is most likely not what you prefer, so you resize the window. Resizing QQuickWindow often looks horrible. It gives a very bad first impression.
4. Stacking order in a virtual Linux
   • The welcome screen goes on top of everything. It's a bit inconvenient to use menus when they go below the welcome screen. It hovers even on top of the Ubuntu dashboard.
5. Resizing Qt Creator in a virtual Linux
   • The first impression is important. The first time you run an application, the window size is most likely not what you prefer, so you resize the window. This gives a horrible first impression.
6. Moving Qt Creator in a virtual Linux
   • One can't even move a window without problems. The content lags somewhere behind and you see some rendering artifacts and what not.
7. Again, stacking order in a virtual Linux
   • I had to add this because it's just so funny. The welcome screen doesn't only float on top of the Ubuntu dashboard, but also on top of the lock screen.

On top of that, there's the endless flow of P1 issues related to popup coordinate mapping. Transient parent windows, effective render windows, render window offsets, window containers. Windows embedded inside windows embedded inside windows... nobody knows how the get the coordinates right.

With widgets the welcome screen would have no rendering issues or popup positioning issues like that. It would just work, even in virtual machines that developers rely on. As a bonus, widgets-based welcome screen probably reduces the startup time of Qt Creator significantly.