Bug 182190 [StatusHandling] [Wizards] getControl assert on wizard page has no message
M6 If you forget to set the control on your wizard page our assert gives no feedback. We need an error message.
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
if (wizard.needsPreviousAndNextButtons()) {
			createPreviousAndNextButtons(parent);
		}
        finishButton = createButton(parent, IDialogConstants.FINISH_ID,
                IDialogConstants.FINISH_LABEL, true);
        cancelButton = createCancelButton(parent);
    }
    
    /* (non-Javadoc)
     * @see org.eclipse.jface.dialogs.Dialog#setButtonLayoutData(org.eclipse.swt.widgets.Button)
     */
    protected void setButtonLayoutData(Button button) {
    	GridData data = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
		int widthHint = convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH);
		
		
		widthHint = Math.min(widthHint, button.getDisplay().getBounds().width / 5);
		Point minSize = button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true);
		data.widthHint = Math.max(widthHint, minSize.x);
		
		
		button.setLayoutData(data);
    }
    /**
     * Creates the Cancel button for this wizard dialog.
     * Creates a standard (<code>SWT.PUSH</code>) button and registers for its
     * selection events. Note that the number of columns in the button bar composite
     * is incremented. The Cancel button is created specially to give it a 
     * removeable listener.
     *