Fix ViewerButtons implicit width calculation

TODO.md

@@ -1,10 +1,8 @@
 # TODO
 
 - Image viewer: 
-    - fix width
     - open externally in context menu in timeline thumbnail, also button
-    - hflickable support kinetic scrolling disabler and speed/decel settings
-    - keyboard controls
+    - hflickable: support kinetic scrolling disabler 
 
 - clipboard preview doesn't update when copied image changes until second time
 - Avatar tooltip can get displayed in front of presence menu

src/gui/Popups/ImageViewerPopup/ViewerButtons.qml

@@ -9,7 +9,7 @@ HFlow {
     property HPopup viewer
 
     readonly property real calculatedWidth:
-        (close.implicitWidth * visibleChildren.length) + theme.spacing
+        utils.sumChildrenImplicitWidths(visibleChildren)
 
 
     HButton {