initial custom action library, "hello, world" quality

installer/adblockplusie.wxs

Index: installer/adblockplusie.wxs
===================================================================
--- a/installer/adblockplusie.wxs
+++ b/installer/adblockplusie.wxs
@@ -89,6 +89,36 @@
     <Property Id="WIXUI_INSTALLDIR" Value="INSTALLFOLDER"/>
 
     <!--
+      Define and schedule a "Custom Action Type 1" to ensure that IE is closed before installation.

[Felix Dahlke, 2013/09/06 16:59:03]

This paragraph describes something that's pretty apparent in the WiX docs, and
it's rather obvious when reading the source IMO. The next paragraph makes sense,
"check" is non-obvious.

+      Because WiX is closely tied to the MSI database format, there are multiple tags required to do this.
+      The "CustomAction" tag defines the tag itself, but doesn't sequence it;
+        it defines an entry in the "CustomAction" table.
+      The "Binary" tag describe an asset that's incorporated into the MSI but that is not an installed component.
+      The "Custom" tag defines the sequencing of an action;
+        it defines an entry in one of the sequence tables (there are six).
+      
+      Attribute "Return" sets the "Custom Action Return Processing Options" to zero,
+        which indicates to block the installer until the action completes
+        and to treat a non-zero return value from the action as an error.
+    -->
+    <CustomAction
+        Id="Close_IE"
+        BinaryKey="installer_ca"
+        DllEntry="abp_close_applications"
+        Return="check"
+    />
+    <Binary Id="installer_ca" SourceFile="..\build\ia32\$(var.Configuration)\installer-ca.dll"/>    
+    <InstallUISequence>
+      <!--
+        The LaunchConditions action occurs near the beginning, before any of the expensive operations.
+      -->
+      <Custom
+        Action="Close_IE"
+        After="LaunchConditions"
+      />
+    </InstallUISequence>
+
+    <!--
       We have only a single feature, since there aren't any optional parts.
       The display is hidden for the same reason; there's nothing to choose from.
     -->