Bug 29755 Attach source does not allow one to select a folder... [build path]
When opening some .class that does not yet have a source attachment eclipse shows a text version of the interface defintion and a button for Attaching source. When pressing this button a window appaer where one can enter the name/location of a folder, zip or jar for the source. There are also a button for choosing it via a file selection dialog and this works fine for zip and jar files - but not for selecting a directory :( Workaround is just to enter the directory manually.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceAttachmentBlock.java
} else {
			fFileNameField.setText(""); 
		}	
	}
	
	private boolean isVariableEntry() {
		return fEntry.getEntryKind() == IClasspathEntry.CPE_VARIABLE;
	}
	
	
	/**
	 * Gets the source attachment path chosen by the user
	 */
	public IPath getSourceAttachmentPath() {
		if (fFileNameField.getText().length() == 0) {
			return null;
		}
		return new Path(fFileNameField.getText());
	}
	/**
	 * Gets the source attachment root chosen by the user
	 * Returns null to let JCore automatically detect the root.
	 */
	public IPath getSourceAttachmentRootPath() {
		return null;
	}
	
		
	/**
	 * Creates the control