From 7fba872bef36903476be033836a8394fd742a1c0 Mon Sep 17 00:00:00 2001
From: fvogel <fvogelnew1@free.fr>
Date: Sat, 26 Dec 2015 20:52:21 +0000
Subject: [.text sync -command $cmd] schedules execution of $cmd by the event
 loop at idle time

---
 generic/tkText.c     | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 generic/tkText.h     |  3 ++-
 generic/tkTextDisp.c | 22 +++++++++++-----------
 3 files changed, 62 insertions(+), 14 deletions(-)

diff --git a/generic/tkText.c b/generic/tkText.c
index a2b7dde..0cb8431 100644
--- a/generic/tkText.c
+++ b/generic/tkText.c
@@ -397,6 +397,7 @@ static int		TextSearchIndexInLine(const SearchSpec *searchSpecPtr,
 static int		TextPeerCmd(TkText *textPtr, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
 static TkUndoProc	TextUndoRedoCallback;
+static void		RunAfterSyncCmd(ClientData clientData);
 
 /*
  * Declarations of the three search procs required by the multi-line search
@@ -1512,8 +1513,8 @@ TextWidgetObjCmd(
 		}
 		textPtr->afterSyncCmd = cmd;
 	    } else {
-		result = Tcl_EvalObjEx(interp, cmd, TCL_EVAL_GLOBAL);
-		Tcl_DecrRefCount(cmd);
+		textPtr->afterSyncCmd = cmd;
+                Tcl_DoWhenIdle(RunAfterSyncCmd, (ClientData) textPtr);
 	    }
 	    break;
 	} else if (objc != 2) {
@@ -6747,6 +6748,52 @@ TkpTesttextCmd(
 }
 
 /*
+ *----------------------------------------------------------------------
+ *
+ * RunAfterSyncCmd --
+ *
+ *	This function is called by the event loop and excutes the command
+ *      scheduled by [.text sync -command $cmd].
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Anything may happen, depending on $cmd contents.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+RunAfterSyncCmd(
+    ClientData clientData)		/* Information about text widget. */
+{
+    register TkText *textPtr = (TkText *) clientData;
+    int code;
+
+    if ((textPtr->tkwin == NULL) || (textPtr->flags & DESTROYED)) {
+        /*
+        * The widget has been deleted. Don't do anything.
+        */
+
+        if (--textPtr->refCount == 0) {
+            ckfree((char *) textPtr);
+        }
+        return;
+    }
+
+    Tcl_Preserve((ClientData) textPtr->interp);
+    code = Tcl_EvalObjEx(textPtr->interp, textPtr->afterSyncCmd, TCL_EVAL_GLOBAL);
+    if (code == TCL_ERROR) {
+        Tcl_AddErrorInfo(textPtr->interp, "\n    (text sync)");
+        Tcl_BackgroundError(textPtr->interp);
+    }
+    Tcl_Release((ClientData) textPtr->interp);
+    Tcl_DecrRefCount(textPtr->afterSyncCmd);
+    textPtr->afterSyncCmd = NULL;
+}
+
+/*
  * Local Variables:
  * mode: c
  * c-basic-offset: 4
diff --git a/generic/tkText.h b/generic/tkText.h
index 49ee479..ea8ce07 100644
--- a/generic/tkText.h
+++ b/generic/tkText.h
@@ -782,7 +782,8 @@ typedef struct TkText {
 				 * statements. */
     int autoSeparators;		/* Non-zero means the separators will be
 				 * inserted automatically. */
-    Tcl_Obj *afterSyncCmd;	/* Command to be executed when lines are up to date */
+    Tcl_Obj *afterSyncCmd;	/* Command to be executed when lines are up to
+                                 * date */
 } TkText;
 
 /*
diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index ba584ac..39311a6 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -2958,18 +2958,18 @@ AsyncUpdateLineMetrics(
 	 * above). If there is a registered aftersync command, run that first.
 	 */
 
-	if (textPtr->afterSyncCmd != NULL) {
-	    int code;
-	    Tcl_Preserve((ClientData)textPtr->interp);
-	    code = Tcl_EvalObjEx(textPtr->interp, textPtr->afterSyncCmd, TCL_EVAL_GLOBAL);
-	    if (code != TCL_OK && code != TCL_CONTINUE
-			&& code != TCL_BREAK) {
-		    Tcl_AddErrorInfo(textPtr->interp, "\n    (text sync)");
-		    Tcl_BackgroundError(textPtr->interp);
+        if (textPtr->afterSyncCmd) {
+            int code;
+            Tcl_Preserve((ClientData) textPtr->interp);
+            code = Tcl_EvalObjEx(textPtr->interp, textPtr->afterSyncCmd,
+                    TCL_EVAL_GLOBAL);
+	    if (code == TCL_ERROR) {
+                Tcl_AddErrorInfo(textPtr->interp, "\n    (text sync)");
+                Tcl_BackgroundError(textPtr->interp);
 	    }
-	    Tcl_Release((ClientData)textPtr->interp);
-	    Tcl_DecrRefCount(textPtr->afterSyncCmd);
-	    textPtr->afterSyncCmd = 0;
+            Tcl_Release((ClientData) textPtr->interp);
+            Tcl_DecrRefCount(textPtr->afterSyncCmd);
+            textPtr->afterSyncCmd = NULL;
 	}
 
         /*
-- 
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