support mouse wheel in lists

src/dlangui/platforms/windows/winapp.d

@@ -737,7 +737,7 @@ LRESULT WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 		case WM_RBUTTONUP:
         case WM_MOUSEWHEEL:
 			if (window !is null) {
-				if (window.onMouse(message, cast(ushort)wParam, cast(short)(lParam & 0xFFFF), cast(short)((lParam >> 16) & 0xFFFF)))
+				if (window.onMouse(message, cast(uint)wParam, cast(short)(lParam & 0xFFFF), cast(short)((lParam >> 16) & 0xFFFF)))
                     return 0; // processed
             }
             // not processed - default handling

src/dlangui/widgets/controls.d

@@ -584,6 +584,21 @@ class ScrollBar : AbstractSlider, OnClickHandler {
         return true;
     }
 
+    /// handle mouse wheel events
+    override bool onMouseEvent(MouseEvent event) {
+        if (visibility != Visibility.Visible)
+            return false;
+        if (event.action == MouseAction.Wheel) {
+            int delta = event.wheelDelta;
+            if (delta > 0)
+                sendScrollEvent(ScrollAction.LineUp, position);
+            else if (delta < 0)
+                sendScrollEvent(ScrollAction.LineDown, position);
+            return true;
+        }
+        return super.onMouseEvent(event);
+    }
+
     /// Draw widget at its position to buffer
     override void onDraw(DrawBuf buf) {
         if (visibility != Visibility.Visible)

src/dlangui/widgets/lists.d

@@ -519,6 +519,10 @@ class ListWidget : WidgetGroup, OnScrollHandler {
 			setHoverItem(-1);
 			return true;
 		}
+        // delegate processing of mouse wheel to scrollbar widget
+        if (event.action == MouseAction.Wheel && _needScrollbar) {
+            return _scrollbar.onMouseEvent(event);
+        }
 		// support onClick
         Rect rc = _pos;
         applyMargins(rc);