Keep previous ButtonToolbarItem-based share toolbar item

Standard toolbar items with `isBordered` enabled do not have a view to
which the share sheet can be pinned.

Author: Eitot

Vienna/Interfaces/Base.lproj/MainWindowController.xib

@@ -264,7 +264,15 @@
                             <action selector="getInfo:" target="-1" id="Xvh-S3-PIS"/>
                         </connections>
                     </toolbarItem>
-                    <toolbarItem implicitItemIdentifier="2194A0A2-BEF2-4411-AE86-F573CC3E7FFB" explicitItemIdentifier="Share" label="Share" paletteLabel="Share" image="NSShareTemplate" bordered="YES" sizingBehavior="auto" id="YVR-Ym-Do7" customClass="VNAToolbarItem">
+                    <toolbarItem implicitItemIdentifier="2194A0A2-BEF2-4411-AE86-F573CC3E7FFB" explicitItemIdentifier="Share" label="Share" paletteLabel="Share" image="NSShareTemplate" sizingBehavior="auto" id="YVR-Ym-Do7" customClass="VNAButtonToolbarItem">
+                        <button key="view" verticalHuggingPriority="750" id="XcR-k5-Au0">
+                            <rect key="frame" x="6" y="14" width="27" height="23"/>
+                            <autoresizingMask key="autoresizingMask"/>
+                            <buttonCell key="cell" type="roundTextured" bezelStyle="texturedRounded" image="NSShareTemplate" imagePosition="only" alignment="center" lineBreakMode="truncatingTail" state="on" borderStyle="border" imageScaling="proportionallyDown" inset="2" id="rk1-Vu-d16">
+                                <behavior key="behavior" pushIn="YES" lightByBackground="YES" lightByGray="YES"/>
+                                <font key="font" metaFont="system"/>
+                            </buttonCell>
+                        </button>
                         <connections>
                             <action selector="invokeSharingServicePicker:" target="-1" id="uUn-Rf-hIQ"/>
                         </connections>

Vienna/Sources/Main window/MainWindowController.swift

@@ -216,11 +216,13 @@ final class MainWindowController: NSWindowController {
     }
 
     @IBAction private func invokeSharingServicePicker(_ sender: Any) {
-        guard sender is NSMenuItem || sender is NSToolbarItem else {
-            return
-        }
-
-        if let window, let contentView = window.contentView {
+        // The sender is either the menu item in the main menu, the menu-form
+        // representation of the toolbar item in label-only mode or the toolbar
+        // item itself.
+        if sender is NSMenuItem || sender is NSToolbarItem,
+            let window,
+            let contentView = window.contentView
+        {
             let picker = NSSharingServicePicker(items: shareableItems)
             picker.delegate = self
             // The menu item does not have a view to which the picker could be
@@ -233,6 +235,16 @@ final class MainWindowController: NSWindowController {
             let yCoordinate = layoutRect.maxY - 1
             let topEdgeRect = NSRect(x: xCoordinate, y: yCoordinate, width: 1, height: 1)
             picker.show(relativeTo: topEdgeRect, of: contentView, preferredEdge: .minY)
+            return
+        }
+
+        // The sender is a button if the user clicked on the toolbar item in
+        // icon-and-label mode or icon-only mode.
+        if let button = sender as? NSButton {
+            let picker = NSSharingServicePicker(items: shareableItems)
+            picker.delegate = self
+            picker.show(relativeTo: .zero, of: button, preferredEdge: .minY)
+            return
         }
     }