bug#53654: 29.0.50; Gtk-CRITICAL warnings with non-Gtk tooltips

[Stephen Berman]

0. emacs -Q
1. evaluate this sexp:
   (let ((use-system-tooltips))
     (tooltip-show "Test"))
=> The shell outputs the following:

(emacs-master:8307): Gtk-CRITICAL **: 10:52:36.874: 
gtk_widget_set_app_paintable: assertion 'GTK_IS_WIDGET (widget)' failed

(emacs-master:8307): Gtk-CRITICAL **: 10:52:36.879: 
gtk_im_context_set_cursor_location: assertion 'GTK_IS_IM_CONTEXT (context)' 
failed

(emacs-master:8307): Gtk-CRITICAL **: 10:52:36.883: 
gtk_im_context_set_cursor_location: assertion 'GTK_IS_IM_CONTEXT (context)' 
failed

This does not happen with emacs-28 (and also doesn't happen in master
with non-nil use-system-tooltips).


In GNU Emacs 29.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.31, cairo 
version 1.17.4)
 of 2022-01-31 built on strobelfs2
Repository revision: 9a56b4e6864c4e0815bb67805cfa67910ab3eeb5
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Linux From Scratch r11.0-115

Configured using:
 'configure --with-xwidgets 'CFLAGS=-Og -g3'
 PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM
XPM XWIDGETS GTK3 ZLIB