widget-factory: This is not a unique app

When running widget-factory a 2nd time, it's usually to compare its
output with a different version of widget-factory.
gtk-demo: This is not a unique app

When running gtk-demo a 2nd time, it's usually to compare its
output with a different version of gtk-demo.
GtkStack: Render a background

https://bugzilla.gnome.org/show_bug.cgi?id=733027
inspector: Reshuffle Visual and General tabs

Move the touchscreen switch to the other debug switches, and
move the hidpi spin to the other graphical controls. Since the
Visual tab is getting large, make it scroll. The General tab
is purely informational again.
Fix the build

gtkx.h can no longer be included internally, so skip it when
generating the gir. We include the individual headers anyway.
widget-factory: Add another listbox example

This one is long enough to scroll, and has selection.
widget-factory: Do no crash on variadic arguments
Updated POTFILES.skip
widget-factory: Add some row activation to the listbox example

This shows some fallout from the gesture conversion.
widget-factory: Demonstrate listbox headers

Add a less trivial examples of headers in the colors listbox.
Trivial typo fix
widget-factory: Fix the row activation example

Turns out ::activate on listbox rows is only for key bindings,
so use ::row-activated.
widget-factory: Improve listbox example spacing
GtkListBox: Add an activatable property for rows

This will let us theme activatable rows differently.
We also avoid emitting the ::row-activated signal for
rows that are not activatable. For compatibility reasons,
rows are activatable by default.

https://bugzilla.gnome.org/show_bug.cgi?id=733112
widget-factory: Use the new ::activatable property
Adwaita: Some theming for activatable list rows
list-box: fix typo in natural size computation
GtkDialog: Set window titles in header bars

This is fallout from the recent dialog changes. We don't set the
headerbar as titlebar early enough anymore, so when the window title
gets set, it does not get passed on to the headerbar. So, re-set it
manually when the titlebar is put in place.

https://bugzilla.gnome.org/show_bug.cgi?id=733099
textiter: remove recursivity of find_by_log_attrs()

find_by_log_attrs() was a recursive function. It is replaced by an
iteration.

The already_moved_initially parameter was TRUE only for the recursive
call, so the paramater is removed.

There is also a small cleanup of the find_visible_by_log_attrs()
(remove trailing spaces, fix indentation).

There is still a part to optimize for a later commit.

https://bugzilla.gnome.org/show_bug.cgi?id=629129
textiter: small optimization for find_by_log_attrs()

Use gtk_text_iter_set_line_offset (&tmp_iter, 0) instead of
gtk_text_iter_get_line(). The difference should not be big. In the first
case the line doesn't need to be traversed thanks to the offset 0. For
get_line(), the btree must be traversed.

A temporary iter is needed to not break the behavior. But the behavior
is quite strange, the function works directly on the iter passed as an
argument to the function, even if the function returns FALSE (not
found). So maybe a later commit will fix this strange behavior.

https://bugzilla.gnome.org/show_bug.cgi?id=629129