fix(DroppableTextArea): fix style and add `clip=true` on Flickable

tests/ui/modules/Common/DroppableTextArea.qml

@@ -36,12 +36,20 @@ Item {
     TextArea.flickable: TextArea {
       id: textArea
 
+      background: Rectangle {
+        color: '#FFFFFF'
+        border.color: '#D0D8DE'
+      }
+
       rightPadding: fileChooserButton.width +
         fileChooserButton.anchors.rightMargin +
         DroppableTextAreaStyle.fileChooserButton.margins
       wrapMode: TextArea.Wrap
     }
     anchors.fill: parent
+
+    // Necessary, else `placeHolderText` can get out of the component.
+    clip: true
   }
 
   // Handle click to select files.

tests/ui/modules/Linphone/Contact/PresenceLevel.qml

 import QtQuick 2.7
 
 import Common 1.0
-import Linphone 1.0 /* It contains `Presence`. */
+import Linphone 1.0
 
 // ===================================================================
 

tests/ui/views/MainWindow/Conversation.qml

@@ -120,14 +120,14 @@ ColumnLayout  {
     }
   }
 
-  Borders {
+  Rectangle {
     Layout.fillWidth: true
-    Layout.preferredHeight: 70
-    borderColor: '#C7C7C7'
-    leftWidth: 1
+    Layout.preferredHeight: 80
+    color: '#E2E9EF'
 
     DroppableTextArea {
       anchors.fill: parent
+      anchors.margins: 10
       placeholderText: qsTr('newMessagePlaceholder')
     }
   }