X-Git-Url: https://git.artsoft.org/?a=blobdiff_plain;f=src%2Flibgame%2Fgadgets.c;h=aaf01eb7e99d70c806f148697b08a82444d27b96;hb=3fb9d9cf97f3d4da6066f3c6b2ce84c81b768982;hp=50dc853129dd107128b5a6f103520758cb46c763;hpb=fda8c9f42aa13663ad6b2f698da787a7280b9965;p=rocksndiamonds.git

diff --git a/src/libgame/gadgets.c b/src/libgame/gadgets.c
index 50dc8531..aaf01eb7 100644
--- a/src/libgame/gadgets.c
+++ b/src/libgame/gadgets.c
@@ -1068,7 +1068,11 @@ static void HandleGadgetTags(struct GadgetInfo *gi, int first_tag, va_list ap)
     getFontCharSource(font_nr, FONT_ASCII_CURSOR, &src_bitmap, &src_x, &src_y);
     src_x += font_width / 2;
     src_y += font_height / 2;
-    gi->selectbox.inverse_color = GetPixel(src_bitmap, src_x, src_y);
+
+    /* there may be esoteric cases with missing or too small font bitmap */
+    if (src_bitmap != NULL &&
+	src_x < src_bitmap->width && src_y < src_bitmap->height)
+      gi->selectbox.inverse_color = GetPixel(src_bitmap, src_x, src_y);
 
     /* always start with closed selectbox */
     gi->selectbox.open = FALSE;
@@ -1713,7 +1717,7 @@ boolean HandleGadgets(int mx, int my, int button)
 
 	if (gs->item_position < 0)
 	  gs->item_position = 0;
-	if (gs->item_position > gs->items_max - gs->items_visible)
+	else if (gs->item_position > gs->items_max - gs->items_visible)
 	  gs->item_position = gs->items_max - gs->items_visible;
 
 	if (old_item_position != gs->item_position)
@@ -1795,13 +1799,22 @@ boolean HandleGadgets(int mx, int my, int button)
 
       gs->position = scrollbar_mouse_pos - gs->drag_position;
 
-      if (gs->position < 0)
+      /* make sure to always precisely reach end positions when dragging */
+      if (gs->position <= 0)
+      {
 	gs->position = 0;
-      if (gs->position > gs->position_max)
+	gs->item_position = 0;
+      }
+      else if (gs->position >= gs->position_max)
+      {
 	gs->position = gs->position_max;
-
-      gs->item_position =
-	gs->items_max * (gs->position + gs->correction) / gs->size_max_cmp;
+	gs->item_position = gs->items_max - gs->items_visible;
+      }
+      else
+      {
+	gs->item_position =
+	  gs->items_max * (gs->position + gs->correction) / gs->size_max_cmp;
+      }
 
       if (gs->item_position < 0)
 	gs->item_position = 0;