Draw image of block when drag-dropping from block tree.
Correct mouseMoveEvent behavior, no functional change.
pothos-gui: make better use of logging facility
Fix segfault when clicking on blank area of block tree.
pothos-gui: make pixmap stack allocated, fix memory leak
pothos-gui: also fix memory leak with painter
pothos-gui: sharedptr to cleanup block after render
pothos-gui: get bounding rectangle for graph obj
pothos-gui: use prerender and bounds for preview pixmap
pothos-gui: use same render quality for preview