[birt-dev] CheckIn: Bugzilla#148766 - NPE thrown out when switch curve f

["Yulin Wang" <yulin.wang@xxxxxxxxxxx>]

- Summary:
NPE thrown out when switch curve fitting setting in chart builder

- Bugzilla Bug (s) Resolved:
148766

- Description:
When switching to another subtask in "format chart" task, the popup with the same name of previous popup will be opened. Meantime, chart model (CurveFittingLine) of new popup may be null.
The fix is to only open the valid popup by checking the enabled status of corresponding toggle button.

- Tests Description: Manual test
- Notes to Build Team: None
- Notes to Developers: None
- Notes to QA: None
- Notes to Documentation: None

- Files Edited:
/org.eclipse.birt.chart.ui.extension/src/org/eclipse/birt/chart/ui/swt/wizard/format/SubtaskSheetImpl.java

- Files Added:

- Files Deleted