Bug 125327 [Dialogs] Error message shown in the InputDialog is not fully visible
When an error message returned by InputValidator is long, InputDialog displays it partially. My suggestion is to create error label with SWT.WRAP flag, or something like this.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/InputDialog.java
/**
     * The title of the dialog.
     */
    private String title;
    /**
     * The message to display, or <code>null</code> if none.
     */
    private String message;
    /**
     * The input value; the empty string by default.
     */
    private String value = "";
    /**
     * The input validator, or <code>null</code> if none.