fixed layout manager so that we know if size got manually changed

fixed scrollframe not sending scroll events to its children
fixed scrollframe scrolling even if mouse is not hovering over the element
improved the behaviour of the flow layout

src/elements/ScrollFrame.lua

@@ -320,20 +320,40 @@ end
 --- @return boolean Whether the event was handled
 --- @protected
 function ScrollFrame:mouse_scroll(direction, x, y)
-    local height = self.get("height")
-    local width = self.get("width")
-    local offsetY = self.get("offsetY")
-    local contentWidth = self.get("contentWidth")
-    local contentHeight = self.get("contentHeight")
+    if self:isInBounds(x, y) then
+        local xOffset, yOffset = self.get("offsetX"), self.get("offsetY")
+        local relX, relY = self:getRelativePosition(x + xOffset, y + yOffset)
 
-    local needsHorizontalScrollBar = self.get("showScrollBar") and contentWidth > width
-    local viewportHeight = needsHorizontalScrollBar and height - 1 or height
-    local maxScroll = math.max(0, contentHeight - viewportHeight)
+        local success, child = self:callChildrenEvent(true, "mouse_scroll", direction, relX, relY)
+        if success then
+            return true
+        end
 
-    local newScroll = math.min(maxScroll, math.max(0, offsetY + direction))
-    self.set("offsetY", newScroll)
+        local height = self.get("height")
+        local width = self.get("width")
+        local offsetY = self.get("offsetY")
+        local offsetX = self.get("offsetX")
+        local contentWidth = self.get("contentWidth")
+        local contentHeight = self.get("contentHeight")
 
-    return true
+        local needsHorizontalScrollBar = self.get("showScrollBar") and contentWidth > width
+        local viewportHeight = needsHorizontalScrollBar and height - 1 or height
+        local needsVerticalScrollBar = self.get("showScrollBar") and contentHeight > viewportHeight
+        local viewportWidth = needsVerticalScrollBar and width - 1 or width
+
+        if needsVerticalScrollBar then
+            local maxScroll = math.max(0, contentHeight - viewportHeight)
+            local newScroll = math.min(maxScroll, math.max(0, offsetY + direction))
+            self.set("offsetY", newScroll)
+        elseif needsHorizontalScrollBar then
+            local maxScroll = math.max(0, contentWidth - viewportWidth)
+            local newScroll = math.min(maxScroll, math.max(0, offsetX + direction))
+            self.set("offsetX", newScroll)
+        end
+
+        return true
+    end
+    return false
 end
 
 --- Renders the ScrollFrame and its scrollbars