src/xdisp.c (draw_row_with_mouse_face): Call
tty_draw_row_with_mouse_face for WINDOWSNT as well.
src/w32console.c: Include window.h.
(w32con_write_glyphs_with_face, tty_draw_row_with_mouse_face): New
functions.
(initialize_w32_display): Initialize mouse-highlight data.
src/w32inevt.c: Include termchar.h and window.h.
(do_mouse_event): Support mouse-autoselect-window. When the mouse
moves, call note_mouse_highlight. If help_echo changed, call
gen_help_event to produce help-echo message in the echo area.
Call clear_mouse_face if mouse_face_hidden is set in the mouse
highlight info.