The as_any() method returning a `&mut dyn Any` meant that the type has to be
'static. The class solution of returning &()
doesn't work because it has to be a mutable ref. Therefore just return an Option.
This ensures that the partial renderer updates correctly and this also
fixes a panic in the printer demo on the stm32h7 when opening the format
combobox in the scan page:
We would attempt to render the word "JPEG" with a font size of 12 pixels.
The letter J has a height of 12 pixels, like the font ascender reported, but it's
y coordinate is negative.
That would also result in a negative text item relative origin for the glyph (target
rect in physical pixels),
which fails to convert to an usize and panics.
When using repeaters - like in the slide puzzle - and during renderer a component
gets deleted, we call free_graphics_resources and try to free
the dirty rectangle list in the partial renderer cache. At that point the cache is
already mutably borrowed, which causes a panic.
As remedy, apply the mutable borrow more fine grained and not right when calling
render().
