[LyX/master] Fix Qt deprecation warning for setItemHidden()

[Scott Kostyshak]

commit 273af8803dd14ffa1b1454c263fa3ac80c9798a6
Author: Scott Kostyshak <skostysh at lyx.org>
Date:   Thu Mar 5 20:29:26 2020 -0500

    Fix Qt deprecation warning for setItemHidden()
    
    Consistent with commit 24926b2e.
---
 src/frontends/qt/GuiPrefs.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/frontends/qt/GuiPrefs.cpp b/src/frontends/qt/GuiPrefs.cpp
index 6b00357..2777300 100644
--- a/src/frontends/qt/GuiPrefs.cpp
+++ b/src/frontends/qt/GuiPrefs.cpp
@@ -3260,7 +3260,7 @@ void PrefShortcuts::on_searchLE_textEdited()
 	// hide everyone (to avoid searching in matched QList repeatedly
 	QTreeWidgetItemIterator it(shortcutsTW, QTreeWidgetItemIterator::Selectable);
 	while (*it)
-		shortcutsTW->setItemHidden(*it++, true);
+		(*it++)->setHidden(true);
 	// show matched items
 	for (int i = 0; i < matched.size(); ++i)
 		if (!isAlwaysHidden(*matched[i])) {