Have a dedicated SendFilePicker component

src/qml/Chat/Composer.qml

@@ -210,16 +210,13 @@ Rectangle {
             icon.name: "upload-file"
             backgroundColor: theme.chat.composer.uploadButton.background
             toolTip.text: qsTr("Send files")
+            onClicked: sendFilePicker.dialog.open()
 
             Layout.fillHeight: true
 
-            HFileDialogOpener {
-                dialog.title: qsTr("Select files to upload")
-                onFilePicked: {
-                    let path = Qt.resolvedUrl(file).replace(/^file:/, "")
-                    let args = [chatPage.roomId, path]
-                    py.callClientCoro(chatPage.userId, "send_file", args)
-                }
+            SendFilePicker {
+                id: sendFilePicker
+                roomId: chatPage.roomId
             }
         }
     }

src/qml/Dialogs/SendFilePicker.qml

@@ -0,0 +1,20 @@
+import QtQuick 2.12
+
+HFileDialogOpener {
+    fill: false
+    dialog.title: qsTr("Select a file to send")
+
+    onFilePicked: {
+        let path = Qt.resolvedUrl(file).replace(/^file:/, "")
+        py.callClientCoro(userId, "send_file", [roomId, path], () => {
+            if (destroyWhenDone) destroy()
+        })
+    }
+
+    onCancelled: if (destroyWhenDone) destroy()
+
+
+    property string userId
+    property string roomId
+    property bool destroyWhenDone: false
+}