feat(ui): add CSimpleSlider::UnregisterRegion

src/ui/CSimpleSlider.cpp

@@ -326,3 +326,11 @@ float CSimpleSlider::Sub96BC10(float value) {
     // TODO
     return value;
 }
+
+void CSimpleSlider::UnregisterRegion(CSimpleRegion* region) {
+    if (this->m_thumbTexture == region) {
+        this->m_thumbTexture = nullptr;
+    }
+
+    this->CSimpleFrame::UnregisterRegion(region);
+}

src/ui/CSimpleSlider.hpp

@@ -33,6 +33,7 @@ class CSimpleSlider : public CSimpleFrame {
         virtual bool IsA(int32_t type);
         virtual int32_t GetScriptMetaTable();
         virtual void LoadXML(XMLNode* node, CStatus* status);
+        virtual void UnregisterRegion(CSimpleRegion* region);
         virtual void OnLayerHide();
         virtual void OnLayerUpdate(float elapsedSec);
         virtual int32_t OnLayerTrackUpdate(const CMouseEvent& evt);