diff --git a/ubb-la/gui.c b/ubb-la/gui.c
index e7834f3..9a94be7 100644
--- a/ubb-la/gui.c
+++ b/ubb-la/gui.c
@@ -45,6 +45,9 @@
 static SDL_Surface *surf;
 
 
+/* ----- SDL initialization and screen-wide functions ---------------------- */
+
+
 void gui_init(void)
 {
 	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
@@ -70,6 +73,16 @@ static void clear(void)
 }
 
 
+static void update(void)
+{
+	SDL_UnlockSurface(surf);
+	SDL_UpdateRect(surf, 0, 0, 0, 0);
+}
+
+
+/* ----- Waveform elements ------------------------------------------------- */
+
+
 static inline int ch_y(int ch, int v)
 {
 	return CH_YOFF+CH_SKIP*ch+(v ? 0 : CH_HEIGHT);
@@ -97,6 +110,9 @@ static void level(int x0, int x1, int ch, int v)
 }
 
 
+/* ----- Show (part of) a buffer ------------------------------------------- */
+
+
 static void show_buffer_zoom_in(const uint8_t *buf, int skip, int nibbles,
     int x0, int x1)
 {
@@ -206,11 +222,7 @@ static void show_buffer(const uint8_t *buf, int skip, int nibbles,
 }
 
 
-static void update(void)
-{
-	SDL_UnlockSurface(surf);
-	SDL_UpdateRect(surf, 0, 0, 0, 0);
-}
+/* ----- Main event loop --------------------------------------------------- */
 
 
 static int pos_step(int zoom)