Gavana, Andrea wrote:

4) Moving the gradient drawing inside EVT_ERASE_BACKGRUND so as to give
the programmer a way to override it (it seems impossible to me,
EVT_ERASE_BACKGRUND does not allow me to do anything *except* calling
"pass" when I use wx.BufferedPaintDC in the Paint. It works with
wx.PaintDC but it flickers like mad);

Yep, I forgot that it doesn't play nice with buffered DCs when I
suggested the change. So I would instead leave the empty
EVT_ERASE_BACKGRUND handler but split up the paint handler so parts of
it can be overridden in a derived class.

5) Possibility to add stretchable spacers between buttons that allows
you to align buttons almost in every way you wish (no idea on how to do it);
6) Adding support of wx.Control inside ButtonPanel (no idea on how to do
it);

5 and 6 are particularly hostile to me because:

1) I can not use sizers (the buttons are not real controls, just images
painted during Paint);

Actually, I just realized that you can use a sizer. When you add an
item to a sizer you get a wx.SizerItem returned to you, even when you
add a spacer. That wx.SizerItem has methods that will give you the
rectangle that the item occupies, so you can add a spacer of the right
size for each of the things that are not real controls (the buttons and
also the main text label for example) and then in the EVT_PAINT handler
access their sizer item to figure out where to draw the item. (You
could save a reference to the sizer item in the ButtonInfo for example.)

2) The combination of ButtonPanel text, possible stretchable spacers,
controls and owner-drawn buttons is driving me crazy. I can't even start
to think about a layout strategy, let's skip the actual coding :-(

This problem goes away with a sizer.

3) The layout is complicated by the fact that if you shrink the
ButtonPanel window, the buttons/controls that can not fit into it should
be hidden/not drawn.

But this becomes more tricky. It's definitely a nice professional
looking feature and I would hate to loose it. To go the sizer route you
would probably have to add code to the EVT_SIZE handler that tests if
the size is too narrow and rebuilds the sizer if needed, or you could
keep the original sizer but change the size of the spacers to (0,0) or
Hide() the controls that need to dissapear, Don't forget to still call
sizer.Layout() from Size since you are overriding the default autosize
behavior.