Collection<? extends ModeSelector> selectors = Lookup.getDefault().lookupAll(ModeSelector.class);

            for (ModeSelector s : selectors) {

                Mode hintMode = s.selectModeForOpen(tc, mode);

                if (hintMode instanceof ModeImpl) {

                    mode = (ModeImpl)hintMode;

                    break;

                }

            }

    <change id="ModeSelector">

        <api name="winsys"/>

        <summary>Allow to select Mode for opening a TopComponent instance</summary>

        <version major="6" minor="6.77"/>

        <date day="2" month="5" year="2017"/>

        <author login="sdedic"/>

        <compatibility addition="yes" semantic="compatible"/>

        <description>

            <p>

                Plugin implementors can direct to-be-opened TopComponents to appropriate Modes or

                prevent them to open in inappropriate Modes.

            </p>

        </description>

        <class package="org.openide.windows" name="ModeSelector"/>

    </change>

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package org.openide.windows;

/**

 * Selects mode which a TopComponent should initially dock into.

 * If a TopComponent being opened is not docked into any Mode, the system selects 

 * the last-used editor-kind Mode, or the default editor mode if no editor was used.

 * Plugin implementors can hint the Window System to use more appropriate

 * mode than the default to open the TopComppnent. 

 * <p/>

 * If none of the registered {@code ModeSelector}s return a valid Mode, the TopComponent

 * will open in the mode selected by the default algorithm. Implementation of WindowManager 

 * may ignore the hint, for example if it conflicts with persisted settings or user choices.

 * <p/>

 * Implementations of {@code ModeSelector} must be registered in the default Lookup.

 * @since 6.77

 */

public interface ModeSelector {

    /**

     * Choose a suitable Mode to open the TopComponent in. The implementation 

     * should return an existing Mode which the TopComponent will dock into. The

     * automatically selected Mode will be passed in {@code preselectedMode}.

     * The implementation can accept the default or ignore the request and return

     * {@code null}.

     * 

     * @param tc the {@link TopComponent} to be opened.

     * @param preselectedMode the default mode for opening

     * @return a more suitable Mode, or {@code null} to use the preselected one.

     */

    public Mode selectModeForOpen(TopComponent tc, Mode preselectedMode);

}