ImageGadget : Fix active not being reset when reverting to stored tile

Changes.md

@@ -10,6 +10,7 @@ Fixes
 -----
 
 - Checkerboard : Checker colors are now exactly equal to the colorA and colorB parameters.  Previously, there were very tiny floating point errors which grew larger as the distance from origin increased.
+- Image Viewer : Fix active tile indicators getting stuck when switching back to cached value partway through compute
 
 0.59.0.0b3 (relative to 0.59.0.0b2)
 ==========

src/GafferImageUI/ImageGadget.cpp

@@ -901,6 +901,11 @@ ImageGadget::Tile::Update ImageGadget::Tile::computeUpdate( const GafferImage::I
 	Mutex::scoped_lock lock( m_mutex );
 	if( m_channelDataHash != MurmurHash() && m_channelDataHash == h )
 	{
+		// We can just keep the current value, since the hash matches.  Set active to false,
+		// in case we were halfway through an update that got cancelled before switching back
+		// to a hash that matches the stored value.
+		m_active = false;
+
 		return Update{ nullptr, nullptr, MurmurHash() };
 	}