SDDM 0.21 still runs its greeter on X11 and sets
QT_IM_MODULE=qtvirtualkeyboard, but since b1eed7f7 the theme only forwards
to Keyboards.KWinVirtualKeyboard, which only exists under a running KWin.
Qt Virtual Keyboard stays loaded as the input method, and because the theme
no longer instantiates its input panel, Qt creates its own
DesktopInputPanel, which pops up whenever a text field gains focus, a plain
mouse click included. The keyboard button was dead there as well, because
KWinVirtualKeyboard.available is false and its visible property never
becomes true.
Bring the X11 fallback back as a theme-private component: on X11
VirtualKeyboard.qml loads the Qt Virtual Keyboard panel that
plasma-workspace dropped in f1c83d15 (instantiating QtVK.InputPanel is what
keeps Qt from creating its own panel), on Wayland it keeps forwarding to
Keyboards.KWinVirtualKeyboard. The button is hidden when no virtual
keyboard is available at all.
The panel itself carries no animation: it is shown and hidden by animating
the loader that holds it, which slides it below the bottom edge while
fading it out. Keeping the animation in one place matters because Qt
Virtual Keyboard's own hide key turns InputMethod.visible off before the
theme is notified, and a panel that hid itself as soon as it became
inactive would disappear in a single frame instead of sliding out. The
panel is only deactivated once it is fully off-screen, so that hiding it
does not cut the animation short.
BUG: 527138
6d3514d331
