Dynamicaly update/blank-out "Send" softkey

I perhaps spent an inordinate amount of time getting this to work
to my satisfaction :P

src/routes/Chat.svelte

@@ -15,7 +15,7 @@
 
   export let params = {}
   let title
-  let centerSoftkeyLabel = 'Send'
+  let centerSoftkeyLabel = ' '
   let chatbox
   let messages
   let chatListEl
@@ -77,12 +77,6 @@
     return k
   })
 
-  $: softkeysStore.update((k) => {
-    k.center.label = centerSoftkeyLabel
-
-    return k
-  })
-
   // Run this and unsubscribe after one
   // second. (The xmppConnected.subscribe function
   // returns the unsubscribe callback, which we
@@ -93,11 +87,54 @@
     }
   }), 1000)
 
+  // Manage the compose box
+
   function onComposeBoxFocus() {
     // scroll to last message, for convenience
     scrollToLatest()
 
-    centerSoftkeyLabel = 'Send'
+    if (!!composeBox) {
+      centerSoftkeyLabel = 'Send'
+    } else {
+      centerSoftkeyLabel = ' '
+    }
+  }
+
+  function updateCenterSoftkeyLabel() {
+    softkeysStore.update((k) => {
+      k.center.label = centerSoftkeyLabel
+
+      return k
+    })
+  }
+
+  function updateComposeLabel() {
+    // We're using 'Send' as a proxy for
+    // checking if the box is focused
+    if (!composeBox && centerSoftkeyLabel == 'Send') {
+      centerSoftkeyLabel = ' ' // hack
+
+      // We have to do this since reactivity
+      // doesn't recurse
+      updateCenterSoftkeyLabel()
+    } else if (!!composeBox && centerSoftkeyLabel == ' ') {
+      centerSoftkeyLabel = 'Send'
+
+      // We have to do this since reactivity
+      // doesn't recurse
+      updateCenterSoftkeyLabel()
+    }
+  }
+
+  $: softkeysStore.update((k) => {
+    k.center.label = centerSoftkeyLabel
+
+    return k
+  })
+
+  $: {
+    !composeBox // whenever this changes
+    updateComposeLabel()
   }
 
   onMount(() => {