From e07d132fbb2cfe30c33750fafbad2f661d854487 Mon Sep 17 00:00:00 2001
From: fvogel <fvogelnew1@free.fr>
Date: Sun, 14 Dec 2014 16:48:25 +0000
Subject: At least one display line is supposed to change when calling
 TkTextChanged.

---
 generic/tkTextDisp.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index f9a28a1..e87b5e8 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -4650,6 +4650,19 @@ TextChanged(
          */
 
         lastPtr = FindDLine(textPtr, dInfoPtr->dLinePtr, &rounded);
+
+        /*
+         * At least one display line is supposed to change. This makes the
+         * redisplay OK in case the display line we expect to get here was
+         * unlinked by a previous call to TkTextChanged and the text widget
+         * did not update before reaching this point. This happens for
+         * instance when moving the cursor up one line.
+         * Note that lastPtr != NULL here, otherwise we would have returned
+         * earlier when we tested for firstPtr being NULL.
+         */
+        if (lastPtr == firstPtr) {
+            lastPtr = lastPtr->nextPtr;
+        }
     }
 
     /*
-- 
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