make all dialog have non-fixed size

this fixes the problem, that some controls may be hidden in some cases, because
dialog size is too small. This can happen when system fonts are bigger
than expected, default system them controls are bigger or if localized
strings are bigger than in English.

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                  <xsd:element name="Win32">

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                    <xsd:complexType>

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                      %(toolchain_gcc)s

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                    </xsd:complexType>

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                  </xsd:element>

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