Running Debian on the WeTab with GNOME Shell without an external keyboard works pretty nicely. The on screen keyboard - if enabled via the accessibility menu - folds out automatically in the shell itself within text input fields. To have this within GTK+3/GTK+2 applications you need libcaribou-gtk3-module and libcaribou-gtk-module installed. For other cases I stitched together a small extension that puts a keyboard "Button" prominently into the middle of the panel. Clicking/touching it will fold it out, clicking again will hide it again. You can fetch it from
git clone git://honk.sigxcpu.org/git/gnome-shell-oskb-extension.git ~/.local/share/gnome-shell/extensions/OnScreenKeyboardButton@sigxcpu.org
and activate it via
gsettings set org.gnome.shell enabled-extensions "['OnScreenKeyboardButton@sigxcpu.org']"
Thanks to the Debian's GNOME packaging team gnome-shell 3.6 is already available in experimental.
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