Bug 9159 Classpath wizard should not complain when adding missing source folder
Build 20020125 - Define a project A with source folder 'src1'. - Go to the .classpath file and edit it to insert one extra line: <classpathentry kind="src" path="src2"/> below the line referring to first source folder: <classpathentry kind="src" path="src1"/>. - Now, try to add this missing source folder 'src2', it isn't allowed by the wizard, one has to add a basic folder instead. Note: It is not such an uncommon scenario, the classpath modification could simply occur by catching up with a shared classpath having one more source folder on it, and which is locally missing.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
fLibrariesPage.init(fCurrJProject);
			fProjectsPage.init(fCurrJProject);
		}		
						
		Composite editorcomp= new Composite(composite, SWT.NONE);	
	
		DialogField[] editors= new DialogField[] { fBuildPathDialogField };
		LayoutUtil.doDefaultLayout(editorcomp, editors, true, 0, 0);
		
		int maxFieldWidth= converter.convertWidthInCharsToPixels(40);
		LayoutUtil.setWidthHint(fBuildPathDialogField.getTextControl(null), maxFieldWidth);
		LayoutUtil.setHorizontalGrabbing(fBuildPathDialogField.getTextControl(null));
	
		editorcomp.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		
		if (fShowSourceFolderPage) {
			folder.setSelection(0);
			fCurrPage= fSourceContainerPage;
		} else {
			folder.setSelection(3);
			fCurrPage= ordpage;
			fClassPathList.selectFirstElement();
		}
		WorkbenchHelp.setHelp(composite, IJavaHelpContextIds.BUILD_PATH_BLOCK);				
		return composite;
	}
	
	private Shell getShell() {
		if (fSWTWidget != null) {
			return fSWTWidget.getShell();