1 files changed, 40 insertions, 10 deletions

diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index c8df68b..93e9c26 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -1170,7 +1170,8 @@ LayoutDLine(
 				 * numBytes > 0. Used to drop 0-sized chunks
 				 * from the end of the line. */
     Tcl_Size byteOffset;
-    int ascent, descent, code, elide, elidesize;
+    int ascent, descent, code, elidesize;
+    bool elide;
     StyleValues *sValuePtr;
     TkTextElideInfo info;	/* Keep track of elide state. */
 
@@ -7357,15 +7358,24 @@ TkTextIndexBbox(
 				 * coordinate. */
     int *widthPtr, int *heightPtr,
 				/* Filled in with index's dimensions. */
-    int *charWidthPtr)		/* If the 'index' is at the end of a display
+    int *charWidthPtr,		/* If the 'index' is at the end of a display
 				 * line and therefore takes up a very large
 				 * width, this is used to return the smaller
 				 * width actually desired by the index. */
+    int *cursorWidthPtr)	/* Receives the same value as 'charWidthPtr'
+				 * except when indexPtr points to a Tab. Then
+				 * 'cursorWidthPtr' gets reduced to the width
+				 * of a single space. */
 {
     TextDInfo *dInfoPtr = textPtr->dInfoPtr;
     DLine *dlPtr;
     TkTextDispChunk *chunkPtr;
     Tcl_Size byteCount;
+    int dummy;
+
+    if (charWidthPtr == NULL) {
+	charWidthPtr = &dummy;
+    }
 
     /*
      * Make sure that all of the screen layout information is up to date.
@@ -7431,20 +7441,16 @@ TkTextIndexBbox(
 	 * line.
 	 */
 
-	if (charWidthPtr != NULL) {
-	    *charWidthPtr = dInfoPtr->maxX - *xPtr;
-	    if (*charWidthPtr > textPtr->charWidth) {
-		*charWidthPtr = textPtr->charWidth;
-	    }
+	*charWidthPtr = dInfoPtr->maxX - *xPtr;
+	if (*charWidthPtr > textPtr->charWidth) {
+	    *charWidthPtr = textPtr->charWidth;
 	}
 	if (*xPtr > dInfoPtr->maxX) {
 	    *xPtr = dInfoPtr->maxX;
 	}
 	*widthPtr = dInfoPtr->maxX - *xPtr;
     } else {
-	if (charWidthPtr != NULL) {
-	    *charWidthPtr = *widthPtr;
-	}
+	*charWidthPtr = *widthPtr;
     }
     if (*widthPtr == 0) {
 	/*
@@ -7472,6 +7478,30 @@ TkTextIndexBbox(
 	    return -1;
 	}
     }
+
+    /*
+     * For a block cursor on a tab, cursorWidthPtr is the whitespace width.
+     */
+
+    if (cursorWidthPtr != NULL) {
+	*cursorWidthPtr = *charWidthPtr;
+	if (chunkPtr->bboxProc == CharBboxProc) {
+	    CharInfo *ciPtr = (CharInfo*)chunkPtr->clientData;
+#ifdef TK_LAYOUT_WITH_BASE_CHUNKS
+	    BaseCharInfo *bciPtr =
+		    (BaseCharInfo*)ciPtr->baseChunkPtr->clientData;
+	    char *chars = Tcl_DStringValue(&bciPtr->baseChars);
+
+	    if (chars[ciPtr->baseOffset + byteCount] == '\t')
+#else
+	    if (ciPtr->chars[byteCount] == '\t')
+#endif
+	    {
+		CharChunkMeasureChars(chunkPtr, " ", 1, 0, 1,
+		    0, -1, 0, cursorWidthPtr);
+	    }
+	}
+    }
     return 0;
 }