From 80e32aa5f98dcdfdda56d05c8bb51c473b518538 Mon Sep 17 00:00:00 2001
From: Eric Mehl <eric@thinkhypothetical.com>
Date: Thu, 19 Oct 2023 17:22:06 -0400
Subject: [PATCH] _LinkedScrollBar : Guard against recursive updates

This may fix #5296 - though I haven't been able to reproduce it. The
problem appears to be endless recursion of `sliderChange()`, which may
have been caused by one of the two scroll bars the `LinkedScrollBar`
manages emitting a change signal that then causes the other scroll bar
to update, emitting a change signal... until the stack overflows.
---
 Changes.md                                    |  4 +-
 .../SpreadsheetUI/_LinkedScrollBar.py         | 38 +++++++++++++++----
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/Changes.md b/Changes.md
index f1d2b4969cb..f4b84d8b3a9 100644
--- a/Changes.md
+++ b/Changes.md
@@ -16,7 +16,9 @@ Improvements
 Fixes
 -----
 
-- Windows : Fixed a bug preventing anything except strings from being copied and pasted.
+- Windows :
+  - Fixed a bug preventing anything except strings from being copied and pasted.
+  - Fixed likely cause of crash when resizing Spreadsheet column width (#5296).
 
 1.3.5.0 (relative to 1.3.4.0)
 =======
diff --git a/python/GafferUI/SpreadsheetUI/_LinkedScrollBar.py b/python/GafferUI/SpreadsheetUI/_LinkedScrollBar.py
index 8b32fde85e5..0b3b0fa70f6 100644
--- a/python/GafferUI/SpreadsheetUI/_LinkedScrollBar.py
+++ b/python/GafferUI/SpreadsheetUI/_LinkedScrollBar.py
@@ -91,23 +91,45 @@ def __init__( self, orientation, scrolledContainers, **kw ) :
 			scrollBar.rangeChanged.connect( Gaffer.WeakMethod( self.__rangeChanged ) )
 			scrollBar.stepsChanged.connect( Gaffer.WeakMethod( self.__stepsChanged ) )
 
+		self.__isUpdating = False
+
 	def __valueChanged( self, value ) :
 
-		for scrollBar in self.__scrollBars :
-			scrollBar.setValue( value )
+		if self.__isUpdating :
+			return
+
+		try :
+			self.__isUpdating = True
+			for scrollBar in self.__scrollBars :
+				scrollBar.setValue( value )
+		finally :
+			self.__isUpdating = False
 
 	def __rangeChanged( self, min, max ) :
 
-		for scrollBar in self.__scrollBars :
-			scrollBar.setRange( min, max )
+		if self.__isUpdating :
+			return
 
-		self.setVisible( min != max )
+		try :
+			self.__isUpdating = True
+			for scrollBar in self.__scrollBars :
+				scrollBar.setRange( min, max )
+			self.setVisible( min != max )
+		finally :
+			self.__isUpdating = False
 
 	def __stepsChanged( self, page, single ) :
 
-		for scrollBar in self.__scrollBars :
-			scrollBar.setPageStep( page )
-			scrollBar.setSingleStep( single )
+		if self.__isUpdating :
+			return
+
+		try :
+			self.__isUpdating = True
+			for scrollBar in self.__scrollBars :
+				scrollBar.setPageStep( page )
+				scrollBar.setSingleStep( single )
+		finally :
+			self.__isUpdating = False
 
 # QScrollBar provides signals for when the value and range are changed,
 # but not for when the page step is changed. This subclass adds the missing