comdlg32: Expand the filetype combobox dropdown to fit the contents.

dlls/comdlg32/comdlg32.rc

@@ -487,7 +487,7 @@ FONT 8, "MS Shell Dlg"
     EDITTEXT        IDC_FILENAME, 226, 240, 100, 12,  WS_CHILD | WS_VISIBLE | WS_TABSTOP
 
     LTEXT           "Files of type:", IDC_FILETYPESTATIC, 160, 256, 60, 9, SS_RIGHT
-    COMBOBOX        IDC_FILETYPE, 226, 256, 100, 12,  WS_CHILD | WS_VISIBLE | WS_TABSTOP |
+    COMBOBOX        IDC_FILETYPE, 226, 256, 100, 12,  WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_VSCROLL |
                     CBS_HASSTRINGS | CBS_DROPDOWNLIST
 
     DEFPUSHBUTTON   "&Open",  IDOK,     350, 240, 40, 14, WS_GROUP

dlls/comdlg32/itemdlg.c

@@ -1535,10 +1535,32 @@ static LRESULT on_wm_initdialog(HWND hwnd, LPARAM lParam)
     hitem = GetDlgItem(This->dlg_hwnd, IDC_FILETYPE);
     if(This->filterspec_count)
     {
-        UINT i;
+        HDC hdc;
+        HFONT font;
+        SIZE size;
+        UINT i, maxwidth = 0;
+
+        hdc = GetDC(hitem);
+        font = (HFONT)SendMessageW(hitem, WM_GETFONT, 0, 0);
+        SelectObject(hdc, font);
+
         for(i = 0; i < This->filterspec_count; i++)
+        {
             SendMessageW(hitem, CB_ADDSTRING, 0, (LPARAM)This->filterspecs[i].pszName);
 
+            if(GetTextExtentPoint32W(hdc, This->filterspecs[i].pszName, lstrlenW(This->filterspecs[i].pszName), &size))
+                maxwidth = max(maxwidth, size.cx);
+        }
+        ReleaseDC(hitem, hdc);
+
+        if(maxwidth > 0)
+        {
+            maxwidth += GetSystemMetrics(SM_CXVSCROLL) + 4;
+            SendMessageW(hitem, CB_SETDROPPEDWIDTH, (WPARAM)maxwidth, 0);
+        }
+        else
+            ERR("Failed to calculate width of filetype dropdown\n");
+
         SendMessageW(hitem, CB_SETCURSEL, This->filetypeindex, 0);
     }
     else