diff -r 3b1da2848fc7 -r d3bac044e0f0 tools/configure/configureapp.cpp
--- a/tools/configure/configureapp.cpp	Fri Feb 19 23:40:16 2010 +0200
+++ b/tools/configure/configureapp.cpp	Fri Mar 12 15:46:37 2010 +0200
@@ -482,6 +482,7 @@
             dictionary[ "BUILDNOKIA" ] = "yes";
             dictionary[ "BUILDDEV" ] = "yes";
             dictionary["LICENSE_CONFIRMED"] = "yes";
+            dictionary[ "SYMBIAN_DEFFILES" ] = "no";
         }
         else if( configCmdLine.at(i) == "-opensource" ) {
             dictionary[ "BUILDTYPE" ] = "opensource";
@@ -803,7 +804,7 @@
         else if( configCmdLine.at(i) == "-no-native-gestures" )
             dictionary[ "NATIVE_GESTURES" ] = "no";
 #if !defined(EVAL)
-        // Others ---------------------------------------------------
+        // Symbian Support -------------------------------------------
         else if (configCmdLine.at(i) == "-fpu" )
         {
             ++i;
@@ -812,12 +813,17 @@
             dictionary[ "ARM_FPU_TYPE" ] = configCmdLine.at(i);
         }
 
-        // S60 Support -------------------------------------------
         else if( configCmdLine.at(i) == "-s60" )
             dictionary[ "S60" ]    = "yes";
         else if( configCmdLine.at(i) == "-no-s60" )
             dictionary[ "S60" ]    = "no";
 
+        else if( configCmdLine.at(i) == "-usedeffiles" )
+            dictionary[ "SYMBIAN_DEFFILES" ] = "yes";
+        else if( configCmdLine.at(i) == "-no-usedeffiles" )
+            dictionary[ "SYMBIAN_DEFFILES" ] = "no";
+
+        // Others ---------------------------------------------------
         else if (configCmdLine.at(i) == "-fast" )
             dictionary[ "FAST" ] = "yes";
         else if (configCmdLine.at(i) == "-no-fast" )
@@ -1471,6 +1477,7 @@
         dictionary[ "XMLPATTERNS" ]         = "yes";
         dictionary[ "QT_GLIB" ]             = "no";
         dictionary[ "S60" ]                 = "yes";
+        dictionary[ "SYMBIAN_DEFFILES" ]    = "yes";
         // iconv makes makes apps start and run ridiculously slowly in symbian emulator (HW not tested)
         // iconv_open seems to return -1 always, so something is probably missing from the platform.
         dictionary[ "QT_ICONV" ]            = "no";
@@ -1825,7 +1832,9 @@
         desc("FREETYPE", "yes",    "-qt-freetype",         "Use the libfreetype bundled with Qt.");
         desc(                      "-fpu <flags>",         "VFP type on ARM, supported options: softvfp(default) | vfpv2 | softvfp+vfpv2");
         desc("S60", "no",          "-no-s60",              "Do not compile in S60 support.");
-        desc("S60", "yes",         "-s60",                 "Compile with support for the S60 UI Framework\n");
+        desc("S60", "yes",         "-s60",                 "Compile with support for the S60 UI Framework");
+        desc("SYMBIAN_DEFFILES", "no",  "-no-usedeffiles",  "Disable the usage of DEF files.");
+        desc("SYMBIAN_DEFFILES", "yes", "-usedeffiles",     "Enable the usage of DEF files.\n");
         return true;
     }
     return false;
@@ -2529,8 +2538,11 @@
             qtConfig += "phonon-backend";
     }
 
-    if (dictionary["MULTIMEDIA"] == "yes")
+    if (dictionary["MULTIMEDIA"] == "yes") {
         qtConfig += "multimedia";
+        if (dictionary["AUDIO_BACKEND"] == "yes")
+            qtConfig += "audio-backend";
+    }
 
     if (dictionary["WEBKIT"] == "yes")
         qtConfig += "webkit";
@@ -2747,6 +2759,13 @@
         if ( dictionary["PLUGIN_MANIFESTS"] == "no" )
             configStream << " no_plugin_manifest";
 
+        if ( dictionary.contains("SYMBIAN_DEFFILES") ) {
+            if(dictionary["SYMBIAN_DEFFILES"] == "yes" ) {
+                configStream << " def_files";
+            } else if ( dictionary["SYMBIAN_DEFFILES"] == "no" ) {
+                configStream << " def_files_disabled";
+            }
+        }
         configStream << endl;
         configStream << "QT_ARCH = " << dictionary[ "ARCHITECTURE" ] << endl;
         if (dictionary["QT_EDITION"].contains("OPENSOURCE"))
@@ -3271,6 +3290,14 @@
         cout << "Support for S60............." << dictionary[ "S60" ] << endl;
     }
 
+    if (dictionary.contains("SYMBIAN_DEFFILES")) {
+        cout << "Symbian DEF files enabled..." << dictionary[ "SYMBIAN_DEFFILES" ] << endl;
+        if(dictionary["SYMBIAN_DEFFILES"] == "no") {
+            cout << "WARNING: Disabling DEF files will mean that Qt is NOT binary compatible with previous versions." << endl;
+            cout << "         This feature is only intended for use during development, NEVER for release builds." << endl;
+        }
+    }
+
     if(dictionary["ASSISTANT_WEBKIT"] == "yes")
         cout << "Using WebKit as html rendering engine in Qt Assistant." << endl;