[BugFix] yesno screen disappears

sending GUI_EVENT_NEED_UI_UPDATE ensured we got redrawn but it also
sometimes resulted in the yesno screen being overdrawn
depending on which event callback was called last

now increasing the update frequency,
clear the dirty bit on whatever vp we are replacing
and well as call our redraw function instead of sending UI_UPDATE

also found a potential bug in get_font()

Change-Id: I1da6defa6db799a4778590daa0c107aba00a9d34

1 files changed, 1 insertions, 1 deletions

diff --git a/firmware/font.c b/firmware/font.c
index 1644201f67..baaec13d3c 100644
--- a/firmware/font.c
+++ b/firmware/font.c
@@ -699,7 +699,7 @@ struct font* font_get(int font)
     struct font* pf;
     if (font == FONT_UI)
         font = MAXFONTS-1;
-    if (font <= FONT_SYSFIXED)
+    if (font <= FONT_SYSFIXED || font >= MAXFONTS)
         return &sysfont;
 
     while (1) {