listbox improvements, tabbing while staying in frame (autoscroll)

graphics/element.lua

@@ -105,6 +105,7 @@ function element.new(args, child_offset_x, child_offset_y)
         value = nil,            ---@type any
         window = nil,           ---@type table
         content_window = nil,   ---@type table|nil
+        mouse_window_shift = { x = 0, y = 0 },
         fg_bg = core.cpair(colors.white, colors.black),
         frame = core.gframe(1, 1, 1, 1),
         children = {},
@@ -344,6 +345,10 @@ function element.new(args, child_offset_x, child_offset_y)
     -- handle this element having been unfocused
     function protected.on_unfocused() end
 
+    -- handle this element having had a child focused
+    ---@param child graphics_element
+    function protected.on_child_focused(child) end
+
     -- handle this element having been shown
     function protected.on_shown() end
 
@@ -520,6 +525,13 @@ function element.new(args, child_offset_x, child_offset_y)
         else args.parent.__focus_child(child) end
     end
 
+    -- a child was focused, used to make sure it is actually visible to the user in the content frame
+    ---@param child graphics_element
+    function public.__child_focused(child)
+        protected.on_child_focused(child)
+        if not self.is_root then args.parent.__child_focused(public) end
+    end
+
     -- get a child element
     ---@nodiscard
     ---@param id element_id
@@ -652,6 +664,7 @@ function element.new(args, child_offset_x, child_offset_y)
         if args.can_focus and protected.enabled and not self.focused then
             self.focused = true
             protected.on_focused()
+            if not self.is_root then args.parent.__child_focused(public) end
         end
     end
 
@@ -704,10 +717,11 @@ function element.new(args, child_offset_x, child_offset_y)
                 end
 
                 local event_T = events.mouse_transposed(event, self.position.x, self.position.y)
-
-                -- handle the mouse event then pass to children
                 protected.handle_mouse(event_T)
-                for _, child in pairs(protected.children) do child.get().handle_mouse(event_T) end
+
+                -- shift child event if the content window has moved then pass to children
+                local c_event_T = events.mouse_transposed(event_T, protected.mouse_window_shift.x + 1, protected.mouse_window_shift.y + 1)
+                for _, child in pairs(protected.children) do child.get().handle_mouse(c_event_T) end
             elseif event.type == events.MOUSE_CLICK.DOWN or event.type == events.MOUSE_CLICK.TAP then
                 -- clicked out, unfocus this element and children
                 public.unfocus_all()