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
if (validator != null) {
            errorMessage = validator.isValid(text.getText());
        }
        
        
        setErrorMessage(errorMessage);
    }
    /**
     * Sets or clears the error message.
     * If not <code>null</code>, the OK button is disabled.
     * 
     * @param errorMessage
     *            the error message, or <code>null</code> to clear
     * @since 3.0
     */
    public void setErrorMessage(String errorMessage) {
    	this.errorMessage = errorMessage;
    	if (errorMessageText != null && !errorMessageText.isDisposed()) {
    		errorMessageText.setText(errorMessage == null ? "" : errorMessage); 
    		errorMessageText.getParent().update();
    		
    		
    		Control button = getButton(IDialogConstants.OK_ID);
    		if (button != null) {
    			button.setEnabled(errorMessage == null);
    		}
    	}
    }
}