See the snapshot below：
To do this, we should use JFace TrayDialog instead of SWT Dialog.The method “setHelpAvailable(boolean helpAvailable)” of TrayDalog indicates whether show the help button on the left-bottom corner on the TrayDilog. So the steps should be:
- Make the dialog extends the TrayDialog.
- In TrayDialog constructor, call method setHelpAvailable(true) to make help button appear.
- Override configureShell(Shell newShell), add PlatformUI.getWorkbench().getHelpSystem().setHelp(newShell, contextHelpID); – The help is for the whole dialog, so should bind the context id with dialog shell.
- Show help content for the focus control in the dialog. In the method createDialogArea(Composite parent) of our dialog, associate related controls with their help contents.(like this way: PlatformUI.getWorkbench().getHelpSystem().setHelp(control, contextHelpID);
- Last and most important one, the initialize dialog size’s height shall not less than 450. If dialog’s height less than 450, helpInfo will be in a pop-up window instead on the right side tray.
PS. We can use PlatformUI.getWorkbench().getHelpSystem().setHelp(control, contextHelpID) method to add different help content for different controls. Therefor, when we press help-button, it will show the help topic of current focused control. If the focused control don’t have help topic, then it will traverse it’s parent control until find a help topic. Of course help-button will do nothing if every control of the dialog has no associated help topic.