GUI: fix piano allowing you to scroll on mobile

extern/imgui_patched/imgui.cpp

@@ -3449,13 +3449,10 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
         g.ActiveIdSource = (g.NavActivateId == id || g.NavActivateInputId == id || g.NavJustMovedToId == id) ? (ImGuiInputSource)ImGuiInputSource_Nav : ImGuiInputSource_Mouse;
         // TODO: check whether this works
         if (g.LastItemData.InFlags & ImGuiItemFlags_NoInertialScroll) {
-          if (window) {
-            window->InertialScrollInhibited=true;
-            printf("inhibiting scroll\n");
-          }
+          g.InertialScrollInhibited=true;
         }
     } else {
-      if (window) window->InertialScrollInhibited=false;
+      g.InertialScrollInhibited=false;
     }
 
     // Clear declaration of inputs claimed by the widget
@@ -5104,6 +5101,11 @@ void ImGui::EndFrame()
         g.DragDropWithinSource = false;
     }
 
+    // Check for inertial scroll inhibit status
+    if (g.IO.MouseReleased[ImGuiMouseButton_Left]) {
+      g.InertialScrollInhibited=false;
+    }
+
     // End frame
     g.WithinFrameScope = false;
     g.FrameCountEnded = g.FrameCount;
@@ -6934,7 +6936,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             if ((g.IO.MouseDown[ImGuiMouseButton_Left] || g.IO.MouseReleased[ImGuiMouseButton_Left]) &&
                 g.ActiveId!=GetWindowScrollbarID(window,ImGuiAxis_X) &&
                 g.ActiveId!=GetWindowScrollbarID(window,ImGuiAxis_Y) &&
-                !window->InertialScrollInhibited) {
+                !g.InertialScrollInhibited) {
               // launch inertial scroll
               if (g.IO.MouseClicked[ImGuiMouseButton_Left]) {
                 window->InertialScrollSpeed=ImVec2(0.0f,0.0f);
@@ -6955,6 +6957,9 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
                   window->InertialScroll=false;
                 }
               }
+            } else if (g.InertialScrollInhibited) {
+              window->InertialScrollSpeed=ImVec2(0.0f,0.0f);
+              window->InertialScroll=false;
             }
           }
 
@@ -6983,9 +6988,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             window->InertialScrollSpeed.x=0.0f;
             window->InertialScrollSpeed.y=0.0f;
           }
-          if (g.IO.MouseReleased[ImGuiMouseButton_Left]) {
-            window->InertialScrollInhibited=false;
-          }
         }
 
         // Apply scrolling
@@ -7554,10 +7556,8 @@ void ImGui::EndDisabled()
 
 void ImGui::InhibitInertialScroll()
 {
-  ImGuiWindow* window = GetCurrentWindow();
-  if (window!=NULL) {
-    window->InertialScrollInhibited=true;
-  }
+  ImGuiContext& g = *GImGui;
+  g.InertialScrollInhibited=true;
 }
 
 // FIXME: Look into renaming this once we have settled the new Focus/Activation/TabStop system.

extern/imgui_patched/imgui_internal.h

@@ -1936,6 +1936,9 @@ struct ImGuiContext
     float                   NavWindowingHighlightAlpha;
     bool                    NavWindowingToggleLayer;
 
+    // Inertial scroll
+    bool                    InertialScrollInhibited;            // Is inertial scroll inhibited? (e.g. by ImGuiItemFlags_NoInertialScroll)
+
     // Render
     float                   DimBgRatio;                         // 0.0..1.0 animation when fading in a dimming background (for modal window and CTRL+TAB list)
     ImGuiMouseCursor        MouseCursor;
@@ -2145,6 +2148,8 @@ struct ImGuiContext
         NavWindowingTimer = NavWindowingHighlightAlpha = 0.0f;
         NavWindowingToggleLayer = false;
 
+        InertialScrollInhibited = false;
+
         DimBgRatio = 0.0f;
         MouseCursor = ImGuiMouseCursor_Arrow;
 
@@ -2295,7 +2300,6 @@ struct IMGUI_API ImGuiWindow
     ImVec2                  ScrollTargetEdgeSnapDist;           // 0.0f = no snapping, >0.0f snapping threshold
     ImVec2                  ScrollbarSizes;                     // Size taken by each scrollbars on their smaller axis. Pay attention! ScrollbarSizes.x == width of the vertical scrollbar, ScrollbarSizes.y = height of the horizontal scrollbar.
     ImVec2                  InertialScrollSpeed;                // current speed of inertial scroll (AKA "swipe")
-    bool                    InertialScrollInhibited;            // Is inertial scroll inhibited? (e.g. by ImGuiItemFlags_NoInertialScroll)
     bool                    ScrollbarX, ScrollbarY;             // Are scrollbars visible?
     bool                    ViewportOwned;
     bool                    Active;                             // Set to true on Begin(), unless Collapsed

extern/imgui_patched/imgui_widgets.cpp

@@ -3113,7 +3113,7 @@ bool ImGui::VSliderScalar(const char* label, const ImVec2& size, ImGuiDataType d
     const ImRect bb(frame_bb.Min, frame_bb.Max + ImVec2(label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f, 0.0f));
 
     ItemSize(bb, style.FramePadding.y);
-    if (!ItemAdd(frame_bb, id))
+    if (!ItemAdd(frame_bb, id, NULL, ImGuiItemFlags_NoInertialScroll))
         return false;
 
     // Default format string when passing NULL

src/gui/piano.cpp

@@ -222,6 +222,7 @@ void FurnaceGUI::drawPiano() {
           bool canInput=false;
           if (ImGui::ItemHoverable(rect,ImGui::GetID("pianoDisplay"))) {
             canInput=true;
+            ImGui::InhibitInertialScroll();
           }
           if (view) {
             int notes=oct*12;