user32: Allow setting horizontal extent even without WS_HSCROLL.

dlls/user32/listbox.c

@@ -83,7 +83,7 @@ typedef struct
     INT         item_height;    /* Default item height */
     INT         page_size;      /* Items per listbox page */
     INT         column_width;   /* Column width for multi-column listboxes */
-    INT         horz_extent;    /* Horizontal extent (0 if no hscroll) */
+    INT         horz_extent;    /* Horizontal extent */
     INT         horz_pos;       /* Horizontal position */
     INT         nb_tabs;        /* Number of tabs in array */
     INT        *tabs;           /* Array of tabs */
@@ -1239,7 +1239,7 @@ static void LISTBOX_SetHorizontalPos( LB_DESCR *descr, INT pos )
  */
 static LRESULT LISTBOX_SetHorizontalExtent( LB_DESCR *descr, INT extent )
 {
-    if (!descr->horz_extent || (descr->style & LBS_MULTICOLUMN))
+    if (descr->style & LBS_MULTICOLUMN)
         return LB_OKAY;
     if (extent <= 0) extent = 1;
     if (extent == descr->horz_extent) return LB_OKAY;
@@ -2485,7 +2485,7 @@ static BOOL LISTBOX_Create( HWND hwnd, LPHEADCOMBO lphc )
     descr->item_height   = 1;
     descr->page_size     = 1;
     descr->column_width  = 150;
-    descr->horz_extent   = (descr->style & WS_HSCROLL) ? 1 : 0;
+    descr->horz_extent   = 0;
     descr->horz_pos      = 0;
     descr->nb_tabs       = 0;
     descr->tabs          = NULL;

dlls/user32/tests/listbox.c

@@ -1617,6 +1617,41 @@ static void test_missing_lbuttonup( void )
     DestroyWindow(parent);
 }
 
+static void test_extents(void)
+{
+    HWND listbox, parent;
+    DWORD res;
+
+    parent = create_parent();
+
+    listbox = create_listbox(WS_CHILD | WS_VISIBLE, parent);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 0, "Got wrong initial horizontal extent: %u\n", res);
+
+    SendMessageA(listbox, LB_SETHORIZONTALEXTENT, 64, 0);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 64, "Got wrong horizontal extent: %u\n", res);
+
+    DestroyWindow(listbox);
+
+
+    listbox = create_listbox(WS_CHILD | WS_VISIBLE | WS_HSCROLL, parent);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 0, "Got wrong initial horizontal extent: %u\n", res);
+
+    SendMessageA(listbox, LB_SETHORIZONTALEXTENT, 64, 0);
+
+    res = SendMessageA(listbox, LB_GETHORIZONTALEXTENT, 0, 0);
+    ok(res == 64, "Got wrong horizontal extent: %u\n", res);
+
+    DestroyWindow(listbox);
+
+    DestroyWindow(parent);
+}
+
 START_TEST(listbox)
 {
   const struct listbox_test SS =
@@ -1698,4 +1733,5 @@ START_TEST(listbox)
   test_set_count();
   test_GetListBoxInfo();
   test_missing_lbuttonup();
+  test_extents();
 }