Firstly, this fixes SVGs painting outside the image view, overlapping
the selection rectangle.
Secondly, it fixes the selection rectangle not painting properly when
fully zoomed in, and sometimes still leaving a rect left over after
zooming back out.
SVG before:
{F5790186, size=full}
SVG after:
{F5790188, size=full}
Raster before:
{F5790189, size=full}
{F5790190, size=full}
Raster after:
{F5790193, size=full}
{F5790194, size=full}