Rework MenuBar. Add MenuButton. Add mouse event cascading to floaters. LinearLayout: spacing now applies to all children, not just those with expand. Fix Window resize request inside layouts. UnicodeGraphics: prepare for styling/theming.

CXXFLAGS=`sdl-config --cflags` -g -Wall -std=c++11 -Isrc
LDFLAGS=`sdl-config --libs` -lSDL_ttf
VPATH=src

demo: demo.cc sdlterm.cc sdlterm.h

clean:
	rm -f demo