Bug 26699 Create Jar fails with no warning if jar read-only
Once *.jardesc has been created, if I invoke "Create JAR" from the context menu and the jar file already exists and is read-only, the progress dialog flashes and nothing more happens. Please add check for this condition and at least an error message should be displayed. Even better, ask something like "Jar file read-only, overwrite?" Y/N and overwrite the file on yes (similar to what the option "warn if jar file exists" does).
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarFileExportOperation.java
}
	protected void saveFiles() {
		
		if (fJarPackage.areClassFilesExported() && fJarPackage.isManifestGenerated() && fJarPackage.isManifestSaved()) {
			try {
				saveManifest();
			} catch (CoreException ex) {
				addError(JarPackagerMessages.getString("JarFileExportOperation.errorSavingManifest"), ex); 
			} catch (IOException ex) {
				addError(JarPackagerMessages.getString("JarFileExportOperation.errorSavingManifest"), ex); 
			}
		}
		
		
		if (fJarPackage.isDescriptionSaved()) {
			try {
				saveDescription();
			} catch (CoreException ex) {
				addError(JarPackagerMessages.getString("JarFileExportOperation.errorSavingDescription"), ex); 
			} catch (IOException ex) {
				addError(JarPackagerMessages.getString("JarFileExportOperation.errorSavingDescription"), ex); 
			}
		}
	}
	private IEditorPart[] getDirtyEditors(Shell parent) {
		Display display= parent.getDisplay();
		final Object[] result= new Object[1];
		display.syncExec(
			new Runnable() {
				public void run() {