user32: A fix for edit controls and long selection strings.

[Michael Moss]

[originally a Picasa patch by Aric Stewart]
---
 dlls/user32/edit.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/dlls/user32/edit.c b/dlls/user32/edit.c
index a5265e9..49f0b04 100644
--- a/dlls/user32/edit.c
+++ b/dlls/user32/edit.c
@@ -3475,6 +3475,11 @@ static void EDIT_EM_ScrollCaret(EDITSTATE *es)
 		INT format_width;
 
 		x = (short)LOWORD(EDIT_EM_PosFromChar(es, es->selection_end, FALSE));
+		if (x < 0)
+		{
+			ERR("Overflow short!\n");
+			return;
+		}
 		format_width = es->format_rect.right - es->format_rect.left;
 		if (x < es->format_rect.left) {
 			goal = es->format_rect.left + format_width / HSCROLL_FRACTION;
@@ -3485,14 +3490,14 @@ static void EDIT_EM_ScrollCaret(EDITSTATE *es)
 			/* FIXME: use ScrollWindow() somehow to improve performance */
 			EDIT_UpdateText(es, NULL, TRUE);
 		} else if (x > es->format_rect.right) {
+			/* scroll edit to display the tail end  of the string */
 			INT x_last;
-			INT len = get_text_length(es);
-			goal = es->format_rect.right - format_width / HSCROLL_FRACTION;
-			do {
-				es->x_offset++;
-				x = (short)LOWORD(EDIT_EM_PosFromChar(es, es->selection_end, FALSE));
-				x_last = (short)LOWORD(EDIT_EM_PosFromChar(es, len, FALSE));
-			} while ((x > goal) && (x_last > es->format_rect.right));
+
+			es->x_offset=0;
+			x = (short)LOWORD(EDIT_EM_PosFromChar(es, es->selection_end, FALSE));
+			x_last = EDIT_CharFromPos(es, x-es->format_rect.right, 1, NULL);
+			es->x_offset = x_last+1;
+
 			/* FIXME: use ScrollWindow() somehow to improve performance */
 			EDIT_UpdateText(es, NULL, TRUE);
 		}
-- 
1.5.3.GIT