Reading panel size

[Tony Houghton <h realh co uk>]

I've wasted a whole evening trying to get my applet to read the size of
the panel.

I started with the facilities provided by the PanelApplet object, but
they're useless, because it only generates "change-size" signals for
certain sizes (multiples of 12?), and panel_applet_get_size() rounds up
to those sizes - except when it rounds down for very small sizes. Maybe
panel_applet_set_size_hints() can fix this, but it's undocumented :-(.

Next I looked at the fish applet, which adds to the PanelApplet a
GtkFrame containing a GtkDrawingArea. It reads the GtkDrawingArea's
allocation and responds to "size-allocate" signals on it.

My applet has a GtkHBox (or VBox for vertical panels) as the outermost
widget within the PanelApplet, containing a number of other widgets
depending on configuration. So I used the box widget's allocation in the
same way as the fish applet. But it always returns a size of 1 and
doesn't generate size-allocate signals. I tried putting the box inside a
GtkFrame (inside the PanelApplet object) with no border, but it didn't
help.

My applet can also be run in a window; in this case the GtkHBox is
inside a GtkEventBox inside the top-level window. This way it works
fine:- the EventBox generates "size-allocate" signals and its allocation
field contains the correct values.

One probably important difference is that the windowed version reads its
start-up size from gconf and adds GtkPixmaps with known size to the
GtkHBox before trying to do anything with allocations.

The trouble is I can't do it in that order with the panel applet because
I don't know how big to make the pixmaps until I know the size of the
panel!

So how am I supposed to read the size of my PanelApplet before adding
any widgets of fixed size to it so that I know what size of widgets to
add?

-- 
TH * http://www.realh.co.uk