Wix Bootstrapper custom Failure Page Message dependent on error code

Having the following WIX Bootstrapper theme:

<?xml version="1.0" encoding="utf-8"?>
<Theme xmlns="http://wixtoolset.org/schemas/thmutil/2010">
    <Window Width="485" Height="300" HexStyle="100a0000" FontId="0">#(loc.Caption)</Window>
    <Font Id="0" Height="-12" Weight="500" Foreground="000000" Background="FFFFFF">Segoe UI</Font>
    <Font Id="1" Height="-24" Weight="500" Foreground="000000">Segoe UI</Font>
    <Font Id="2" Height="-22" Weight="500" Foreground="666666">Segoe UI</Font>
    <Font Id="3" Height="-12" Weight="500" Foreground="000000" Background="FFFFFF">Segoe UI</Font>
    <Font Id="4" Height="-12" Weight="500" Foreground="ff0000" Background="FFFFFF" Underline="yes">Segoe UI</Font>

    <Image X="11" Y="11" Width="64" Height="64" ImageFile="logo.png" Visible="yes"/>
    <Text X="80" Y="11" Width="-11" Height="64" FontId="1" Visible="yes">#(loc.Title)</Text>

    <Page Name="Install">
        <Richedit Name="EulaRichedit" X="11" Y="80" Width="-11" Height="-70" TabStop="yes" FontId="0" HexStyle="0x800000" />
        <Checkbox Name="EulaAcceptCheckbox" X="-11" Y="-41" Width="246" Height="17" TabStop="yes" FontId="3" HideWhenDisabled="yes">#(loc.InstallAcceptCheckbox)</Checkbox>
        <Button Name="OptionsButton" X="-171" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.InstallOptionsButton)</Button>
        <Button Name="InstallButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.InstallInstallButton)</Button>
        <Button Name="WelcomeCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.InstallCloseButton)</Button>
    </Page>

    <Page Name="Options">
        <Text X="11" Y="80" Width="-11" Height="30" FontId="2">#(loc.OptionsHeader)</Text>
        <Text X="11" Y="121" Width="-11" Height="17" FontId="3">#(loc.OptionsLocationLabel)</Text>
        <Editbox Name="FolderEditbox" X="11" Y="143" Width="-91" Height="21" TabStop="yes" FontId="3" FileSystemAutoComplete="yes" />
        <Button Name="BrowseButton" X="-11" Y="142" Width="75" Height="23" TabStop="yes" FontId="3">#(loc.OptionsBrowseButton)</Button>
        <Button Name="OptionsOkButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.OptionsOkButton)</Button>
        <Button Name="OptionsCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.OptionsCancelButton)</Button>
    </Page>

    <Page Name="Progress">
        <Text X="11" Y="80" Width="-11" Height="30" FontId="2">#(loc.ProgressHeader)</Text>
        <Text X="11" Y="121" Width="70" Height="17" FontId="3">#(loc.ProgressLabel)</Text>
        <Text Name="OverallProgressPackageText" X="85" Y="121" Width="-11" Height="17" FontId="3">#(loc.OverallProgressPackageText)</Text>
        <Progressbar Name="OverallCalculatedProgressbar" X="11" Y="143" Width="-11" Height="15" />
        <Button Name="ProgressCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.ProgressCancelButton)</Button>
    </Page>

    <Page Name="Modify">
        <Text X="11" Y="80" Width="-11" Height="30" FontId="2">#(loc.ModifyHeader)</Text>
        <Button Name="RepairButton" X="-171" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.ModifyRepairButton)</Button>
        <Button Name="UninstallButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.ModifyUninstallButton)</Button>
        <Button Name="ModifyCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.ModifyCloseButton)</Button>
    </Page>

    <Page Name="Success">
        <Text X="11" Y="80" Width="-11" Height="30" FontId="2">#(loc.SuccessHeader)</Text>
        <Button Name="LaunchButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.SuccessLaunchButton)</Button>
        <Text Name="SuccessRestartText" X="-11" Y="-51" Width="400" Height="34" FontId="3" HideWhenDisabled="yes">#(loc.SuccessRestartText)</Text>
        <Button Name="SuccessRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.SuccessRestartButton)</Button>
        <Button Name="SuccessCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.SuccessCloseButton)</Button>
    </Page>

    <Page Name="Failure">
        <Text X="11" Y="80" Width="-11" Height="30" FontId="2">#(loc.FailureHeader)</Text>
        <Hypertext Name="FailureLogFileLink" X="11" Y="121" Width="-11" Height="42" FontId="3" TabStop="yes" HideWhenDisabled="yes">#(loc.FailureHyperlinkLogText)</Hypertext>
        <Hypertext Name="FailureMessageText" X="22" Y="163" Width="-11" Height="51" FontId="3" TabStop="yes" HideWhenDisabled="yes" />
        <Text Name="FailureRestartText" X="-11" Y="-51" Width="400" Height="34" FontId="3" HideWhenDisabled="yes">#(loc.FailureRestartText)</Text>
        <Button Name="FailureRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.FailureRestartButton)</Button>
        <Button Name="FailureCloseButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.FailureCloseButton)</Button>
    </Page>
</Theme>

What do I need to do to have a custom error message when user clicks cancel?

I basically need a condition to evaluate the case where FailureMessageText is "0x80070642 - User cancelled installation"

The failure window should then display "Installation Cancelled by User" instead of "Setup Failed"

Is there any way to evaluate above expression inside the theme and display controls based on a certain condition ?

*EDIT - 30 jan 2014 *

Here is the problem element:

<Page Name="Failure">
...
  <Hypertext Name="FailureMessageText" X="22" Y="163" Width="-11" Height="51" FontId="3" TabStop="yes" HideWhenDisabled="yes" />
...
</Page>

I could write:

<Page Name="Failure">
...
  <Text Name="MyCustomText" X="-11" Y="-51" Width="400" Height="34" FontId="3" HideWhenDisabled="yes"> My custom message </Text>
...
</Page>

but this will not check if error code is 0x80070642 (user cancelled installation), it is just another hard-coded message.

To display the custom error messages you need to change the messages in WixBootstrapperTheme.wxl file which is pointed by LocalizationFile attribute.

<Bundle ...>
.................
<BootstrapperApplicationRef Id="WixStandardBootstrapperApplication.RtfLicense">
      <bal:WixStandardBootstrapperApplication
        LicenseUrl=""
        LogoFile="Logo.png"
        SuppressOptionsUI="yes"
        LocalizationFile="BootstrapTheme.wxl"
        ThemeFile="BootstrapTheme.xml"/>
    </BootstrapperApplicationRef>
................
</Bundle>