participantslayer: fix visibility of buttons

If a participant is maximised and minimized while active, the
button is not correctly displayed

Change-Id: I15a32e4f2bbbcd49b3448fb7f241edb6ad37250b

src/mainview/components/ParticipantsLayer.qml

@@ -131,6 +131,7 @@ Item {
                     radius: 10
                     text: "<"
                     visible: genericParticipantsRect.currentPos > 0
+                             && activeParticipantsFlow.visible
                     onClicked: {
                         if (genericParticipantsRect.currentPos > 0)
                             genericParticipantsRect.currentPos--
@@ -239,6 +240,7 @@ Item {
                     radius: 10
                     text: ">"
                     visible: genericParticipantsRect.topLimit - genericParticipantsRect.showable > genericParticipantsRect.currentPos
+                             && activeParticipantsFlow.visible
                     onClicked: {
                         if (genericParticipantsRect.topLimit - genericParticipantsRect.showable > genericParticipantsRect.currentPos)
                             genericParticipantsRect.currentPos++