Bug 33550 [Dialogs] Dialog should support remembering size and position
There are several dialogs that remember its size and position. Since restore the size and considering screen size and font changes isn't trivial JFace's Dialog class should support remembering and restoring size and position. These would realy ease the task for subclasses. May be you can steel the code from OpenTypeSelectionDialog.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/ResourceListSelectionDialog.java
/**
     * Gets the dialog settings section for this dialog, and creates it if
     * it does not exist yet.
     * 
     * @param dialogSettingsSectionName the section name of this dialog's dialog settings.
     * 
     * @since 3.2
     */
    private IDialogSettings getDialogSettings(String dialogSettingsSectionName) {
        IDialogSettings settings = IDEWorkbenchPlugin.getDefault().getDialogSettings();
        IDialogSettings section = settings.getSection(dialogSettingsSectionName);
        if (section == null) {
            section = settings.addNewSection(dialogSettingsSectionName);
        } 
        return section;
    }
    
    /**
     * Saves the location and dimensions of the shell in the
     * IDE dialog settings.
     * 
     * @param shell The shell whose geometry is to be stored
     * 
     * @since 3.2
     */
    private void saveDialogSettings(Shell shell) {
        Point shellLocation = shell.getLocation();
        Point shellSize = shell.getSize();
        IDialogSettings settings = getDialogSettings(DIALOG_SETTINGS_SECTION);
        settings.put(DIALOG_ORIGIN_X, shellLocation.x);