winecfg: Enable add button when choosing lib from combobox (Libraries tabsheet).

programs/winecfg/libraries.c

@@ -408,10 +408,14 @@ static void init_libsheet(HWND dialog)
 static void on_add_combo_change(HWND dialog)
 {
     char buffer[1024];
+    int sel, len;
 
     SendDlgItemMessage(dialog, IDC_DLLCOMBO, WM_GETTEXT, sizeof(buffer), (LPARAM) buffer);
+    /* if lib was chosen from combobox, we reveive an empty buffer, check manually */
+    sel=SendDlgItemMessage(dialog, IDC_DLLCOMBO, CB_GETCURSEL, 0, 0);
+    len=SendDlgItemMessage(dialog, IDC_DLLCOMBO, CB_GETLBTEXTLEN, sel, 0);
 
-    if (strlen(buffer))
+    if (strlen(buffer)>0 || len>0)
         enable(IDC_DLLS_ADDDLL)
     else
         disable(IDC_DLLS_ADDDLL);