src/vs/editor/contrib/find/browser/findWidget.ts/FindWidget/_updateToggleSelectionFindButton
class FindWidget:	private _updateToggleSelectionFindButton(): void {
		const selection = this._codeEditor.getSelection();
		const isSelection = selection ? (selection.startLineNumber !== selection.endLineNumber || selection.startColumn !== selection.endColumn) : false;
		const isChecked = this._toggleSelectionFind.checked;

		if (this._isVisible && (isChecked || isSelection)) {
			this._toggleSelectionFind.enable();
		} else {
			this._toggleSelectionFind.disable();
		}
	}