created an attachment (id=163375)
screenshot

description:
expression lost in aggregation builder when measure is removed from crosstab.

regression of #279889

build number:
2.6.0.v20100330-0630

steps to reproduce:
1. new a crosstab.
2. right click the measure area and remove the measure from the crosstab.
3. double click the measure binding in property editor.

expected result:
the expression is shown.

actual result:
the expression is lost (see the screenshot).

error log:
n/a
fixed it.
verified in build (2.5.3.v20100409-0302).
exception is thrown out in build (2.6.0.v20100409-0630) when double click the measure binding in property editor.

reopen for further investigation.

error log:
java.lang.nullpointerexception
at org.eclipse.birt.report.item.crosstab.internal.ui.dialogs.crosstabbindingdialoghelper.getcrosstabviewhandlelevels(crosstabbindingdialoghelper.java:449)
at org.eclipse.birt.report.item.crosstab.internal.ui.dialogs.crosstabbindingdialoghelper.getaggons(crosstabbindingdialoghelper.java:408)
at org.eclipse.birt.report.item.crosstab.internal.ui.dialogs.crosstabbindingdialoghelper.initaggon(crosstabbindingdialoghelper.java:336)
at org.eclipse.birt.report.item.crosstab.internal.ui.dialogs.crosstabbindingdialoghelper.initdialog(crosstabbindingdialoghelper.java:295)
at org.eclipse.birt.report.designer.internal.ui.dialogs.datacolumnbindingdialog.initdialog(datacolumnbindingdialog.java:346)
at org.eclipse.birt.report.designer.ui.dialogs.basedialog.open(basedialog.java:102)
at org.eclipse.birt.report.designer.internal.ui.views.attributes.provider.aggregateonbindingsformhandleprovider.doedititem(aggregateonbindingsformhandleprovider.java:73)
at org.eclipse.birt.report.designer.internal.ui.views.attributes.provider.abstractsortingformhandleprovider.edit(abstractsortingformhandleprovider.java:68)
at org.eclipse.birt.report.designer.internal.ui.views.attributes.widget.sortingformpropertydescriptor.edit(sortingformpropertydescriptor.java:456)
at org.eclipse.birt.report.designer.internal.ui.views.attributes.widget.sortingformpropertydescriptor.handleeditselectevent(sortingformpropertydescriptor.java:881)
at org.eclipse.birt.report.designer.internal.ui.views.attributes.widget.sortingformpropertydescriptor$7.widgetselected(sortingformpropertydescriptor.java:421)
at org.eclipse.swt.widgets.typedlistener.handleevent(typedlistener.java:228)
at org.eclipse.swt.widgets.eventtable.sendevent(eventtable.java:84)
at org.eclipse.swt.widgets.widget.sendevent(widget.java:1050)
at org.eclipse.swt.widgets.display.rundeferredevents(display.java:4037)
at org.eclipse.swt.widgets.display.readanddispatch(display.java:3628)
at org.eclipse.ui.internal.workbench.runeventloop(workbench.java:2416)
at org.eclipse.ui.internal.workbench.runui(workbench.java:2380)
at org.eclipse.ui.internal.workbench.access$4(workbench.java:2229)
at org.eclipse.ui.internal.workbench$5.run(workbench.java:504)
at org.eclipse.core.databinding.observable.realm.runwithdefault(realm.java:332)
at org.eclipse.ui.internal.workbench.createandrunworkbench(workbench.java:497)
at org.eclipse.ui.platformui.createandrunworkbench(platformui.java:149)
at org.eclipse.ui.internal.ide.application.ideapplication.start(ideapplication.java:115)
at org.eclipse.equinox.internal.app.eclipseapphandle.run(eclipseapphandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.eclipseapplauncher.runapplication(eclipseapplauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.eclipseapplauncher.start(eclipseapplauncher.java:79)
at org.eclipse.core.runtime.adaptor.eclipsestarter.run(eclipsestarter.java:369)
at org.eclipse.core.runtime.adaptor.eclipsestarter.run(eclipsestarter.java:179)
at sun.reflect.nativemethodaccessorimpl.invoke0(native method)
at sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:39)
at sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:25)
at java.lang.reflect.method.invoke(method.java:597)
at org.eclipse.equinox.launcher.main.invokeframework(main.java:619)
at org.eclipse.equinox.launcher.main.basicrun(main.java:574)
at org.eclipse.equinox.launcher.main.run(main.java:1406)
fixed it.

i can't reproduce the bug, but still do a null point check in the code.
verified in build (2.6.0.v20100414-0630), closed.