Make sure the minibuffer doesn't allow styles to bleed through

The minibuffer is another user of the overlay widget, and I need to
configure it to unilaterally use the style of the upper canvas. Without
this setting, the bold cursor position in the hex view below can bleed
through.

widgets/minibuffer/minibuffer.go

@@ -457,7 +457,11 @@ func (w *Widget) updateCompletions(app gowid.IApp) {
 func Open(w *Widget, container gowid.ISettableComposite, width gowid.IWidgetDimension, app gowid.IApp) {
 	w.ov = overlay.New(w, container.SubWidget(),
 		gowid.VAlignBottom{}, gowid.RenderWithUnits{U: 3}, // Intended to mean use as much vertical space as you need
-		gowid.HAlignLeft{Margin: 5, MarginRight: 5}, width)
+		gowid.HAlignLeft{Margin: 5, MarginRight: 5}, width,
+		overlay.Options{
+			IgnoreLowerStyle: true,
+		},
+	)
 
 	if _, ok := width.(gowid.IRenderFixed); ok {
 		w.SetContentWidth(gowid.RenderFixed{}, app) // fixed or weight:1, ratio:0.5