Fix flickering in debug panel

This flickering made debug panel unusable, because most of the time
panel was white. This problem effects wxPython with GTK3+ backend
(at least on GNU/Linux systems).

Removed code IIUC draws box with content of moved debug variable, I
don't see any effect of it neither on GNU/Linux nor on Windows. It
should be safe to remove.

                  <xsd:element name="Win32">
                    <xsd:complexType>
                      %(toolchain_gcc)s
                    </xsd:complexType>
                  </xsd:element>