From acc6addb86dff7a6b1969174f6ed0f9d60ad48ab Mon Sep 17 00:00:00 2001
From: attila <attila@juce.com>
Date: Wed, 3 Aug 2022 20:32:13 +0200
Subject: [PATCH] DragAndDropContainer:  Manage keyboard focus for the drag
 image when the target needs it hidden

The previous implementation would trigger assertions in
grabKeyboardFocus() when the DragImageComponent was hidden due to the
target returning false from shouldDrawDragImageWhenOver().

Hiding the image would also mean that its keyboard focus was lost. Now
focus is restored when the image becomes visible again.
---
 .../mouse/juce_DragAndDropContainer.cpp             | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/modules/juce_gui_basics/mouse/juce_DragAndDropContainer.cpp b/modules/juce_gui_basics/mouse/juce_DragAndDropContainer.cpp
index e534e1909e..d2b5bb268f 100644
--- a/modules/juce_gui_basics/mouse/juce_DragAndDropContainer.cpp
+++ b/modules/juce_gui_basics/mouse/juce_DragAndDropContainer.cpp
@@ -138,6 +138,8 @@ public:
 
         setVisible (newTarget == nullptr || newTarget->shouldDrawDragImageWhenOver());
 
+        maintainKeyboardFocusWhenPossible();
+
         if (newTargetComp != currentlyOverComp)
         {
             if (auto* lastTarget = getCurrentlyOver())
@@ -233,6 +235,16 @@ private:
     Time lastTimeOverTarget;
     int originalInputSourceIndex;
     MouseInputSource::InputSourceType originalInputSourceType;
+    bool canHaveKeyboardFocus = false;
+
+    void maintainKeyboardFocusWhenPossible()
+    {
+        const auto newCanHaveKeyboardFocus = isVisible();
+
+        if (std::exchange (canHaveKeyboardFocus, newCanHaveKeyboardFocus) != newCanHaveKeyboardFocus)
+            if (canHaveKeyboardFocus)
+                grabKeyboardFocus();
+    }
 
     void updateSize()
     {
@@ -489,7 +501,6 @@ void DragAndDropContainer::startDragging (const var& sourceDescription,
 
     dragImageComponent->sourceDetails.localPosition = sourceComponent->getLocalPoint (nullptr, lastMouseDown);
     dragImageComponent->updateLocation (false, lastMouseDown);
-    dragImageComponent->grabKeyboardFocus();
 
    #if JUCE_WINDOWS
     // Under heavy load, the layered window's paint callback can often be lost by the OS,