The only way I managed to handle an icon with zenity is with --notification as follow
$ cat zenity-test.sh
#!/bin/sh
cat <<EOH| zenity --notification --listen
icon: /usr/share/icons/gnome/32x32/categories/applications-internet.png
message: this is the message text
tooltip: this is the tooltip text
EOH
this create two notification dialogs (right top corner in Unity) with the icon appearing to the left of the text.
No luck with dialogs and form-based widgets.
Ubuntu 14.04.2 LTS
zenity 3.8.0
this bug is still present.
The only way I managed to handle an icon with zenity is with --notification as follow
$ cat zenity-test.sh
#!/bin/sh
cat <<EOH| zenity --notification --listen icons/gnome/ 32x32/categorie s/applications- internet. png
icon: /usr/share/
message: this is the message text
tooltip: this is the tooltip text
EOH
this create two notification dialogs (right top corner in Unity) with the icon appearing to the left of the text.
No luck with dialogs and form-based widgets.