Remove unused x/y textboxclass attributes

These unused variables distract from properly analyzing the code when
you read it, since the xp/yp attributes of textboxclass already exist,
too.

desktop_version/src/Textbox.cpp

@@ -4,8 +4,6 @@
 
 textboxclass::textboxclass(void)
 {
-    x = 0;
-    y = 0;
     w = 0;
     h = 0;
     lw = 0;