Let buttons catch touchStart

Resolves https://github.com/EdgeTX/edgetx/issues/1087

radio/src/thirdparty/libopenui/src/button.cpp

@@ -47,6 +47,14 @@ void Button::onEvent(event_t event)
 }
 #endif
 
+#if defined(HARDWARE_TOUCH)
+bool Button::onTouchStart(coord_t x, coord_t y)
+{
+  Window::onTouchStart(x, y);
+  return true;
+}
+#endif
+
 #if defined(HARDWARE_TOUCH)
 bool Button::onTouchEnd(coord_t x, coord_t y)
 {

radio/src/thirdparty/libopenui/src/button.h

@@ -74,6 +74,7 @@ class Button: public FormField
 #endif
 
 #if defined(HARDWARE_TOUCH)
+    bool onTouchStart(coord_t x, coord_t y) override;
     bool onTouchEnd(coord_t x, coord_t y) override;
 #endif