import { Widget } from '@lumino/widgets';
export declare const WidgetContextKeyContribution: unique symbol;
/**
 * Contributes the context key values that describe a particular widget, so that `when` clauses about
 * that widget - such as the ones of its tab bar toolbar items - can be evaluated without consulting the
 * ambient context, which describes whichever widget currently has focus.
 */
export interface WidgetContextKeyContribution {
    /**
     * @param widget the widget to describe.
     * @returns the values to overlay over the ambient context, or `undefined` if this contribution does not
     * describe the given widget. A contribution owning a key should return an explicit "unset" value for the
     * widgets the key does not apply to, so that the ambient value of another widget cannot leak in.
     */
    getContextKeyValues(widget: Widget): Iterable<[string, unknown]> | undefined;
}
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