fix scroll-x on touchpad (prevent bubbling scroll-y events and lock f…

…urther wheeling events to parent window, if children window has interest for scroll-x)

imgui.cpp

@@ -3655,28 +3655,22 @@ void ImGui::UpdateMouseWheel()
     // If a child window has the ImGuiWindowFlags_NoScrollWithMouse flag, we give a chance to scroll its parent
 
     // Vertical Mouse Wheel scrolling
-    const float wheel_y = (g.IO.MouseWheel != 0.0f && !g.IO.KeyShift) ? g.IO.MouseWheel : 0.0f;
-    if (wheel_y != 0.0f && !g.IO.KeyCtrl)
+    const float wheel_y = (!g.IO.KeyShift) ? g.IO.MouseWheel : 0.0f;
+    // Horizontal Mouse Wheel scrolling, or Vertical Mouse Wheel w/ Shift held
+    const float wheel_x = (!g.IO.KeyShift) ? g.IO.MouseWheelH : g.IO.MouseWheel;
+    if ((wheel_y != 0.0f || wheel_x != 0.0f) && !g.IO.KeyCtrl)
     {
-        StartLockWheelingWindow(window);
-        while ((window->Flags & ImGuiWindowFlags_ChildWindow) && ((window->ScrollMax.y == 0.0f) || ((window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(window->Flags & ImGuiWindowFlags_NoMouseInputs))))
+        bool noScroll = (window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(window->Flags & ImGuiWindowFlags_NoMouseInputs);
+        while ((window->Flags & ImGuiWindowFlags_ChildWindow) && ((window->ScrollMax.y == 0.0f && window->ScrollMax.x == 0.0f) || noScroll))
             window = window->ParentWindow;
-        if (!(window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(window->Flags & ImGuiWindowFlags_NoMouseInputs))
+        StartLockWheelingWindow(window);
+        if (!noScroll && wheel_y != 0.0f)
         {
             float max_step = window->InnerRect.GetHeight() * 0.67f;
             float scroll_step = ImFloor(ImMin(5 * window->CalcFontSize(), max_step));
             SetScrollY(window, window->Scroll.y - wheel_y * scroll_step);
         }
-    }
-
-    // Horizontal Mouse Wheel scrolling, or Vertical Mouse Wheel w/ Shift held
-    const float wheel_x = (g.IO.MouseWheelH != 0.0f && !g.IO.KeyShift) ? g.IO.MouseWheelH : (g.IO.MouseWheel != 0.0f && g.IO.KeyShift) ? g.IO.MouseWheel : 0.0f;
-    if (wheel_x != 0.0f && !g.IO.KeyCtrl)
-    {
-        StartLockWheelingWindow(window);
-        while ((window->Flags & ImGuiWindowFlags_ChildWindow) && ((window->ScrollMax.x == 0.0f) || ((window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(window->Flags & ImGuiWindowFlags_NoMouseInputs))))
-            window = window->ParentWindow;
-        if (!(window->Flags & ImGuiWindowFlags_NoScrollWithMouse) && !(window->Flags & ImGuiWindowFlags_NoMouseInputs))
+        if (!noScroll && wheel_x != 0.0f)
         {
             float max_step = window->InnerRect.GetWidth() * 0.67f;
             float scroll_step = ImFloor(ImMin(2 * window->CalcFontSize(), max_step));