Added an option to pass -1 as the hoverTimeout parameter of Slider::setPopupDisplayEnabled() to cause the popup to remain until a mouseExit() and added some documentation

modules/juce_gui_basics/widgets/juce_Slider.cpp

@@ -965,7 +965,7 @@ public:
                 if (popupDisplay == nullptr)
                     showPopupDisplay();
 
-                if (popupDisplay != nullptr)
+                if (popupDisplay != nullptr && popupHoverTimeout != -1)
                     popupDisplay->startTimer (popupHoverTimeout);
             }
         }

modules/juce_gui_basics/widgets/juce_Slider.h

@@ -626,6 +626,10 @@ public:
         pass nullptr, the pop-up will be placed on the desktop instead (note that it's a
         transparent window, so if you're using an OS that can't do transparent windows
         you'll have to add it to a parent component instead).
+
+        By default the popup display shown when hovering will remain visible for 2 seconds,
+        but it is possible to change this by passing a different hoverTimeout value. A
+        value of -1 will cause the popup to remain until a mouseExit() occurs on the slider.
     */
     void setPopupDisplayEnabled (bool shouldShowOnMouseDrag,
                                  bool shouldShowOnMouseHover,