Use ellipsis-msg instead of message%.

There's a 200 character contract for message% -> set-label.

info.rkt

@@ -21,6 +21,7 @@
     "racket-sonos"
     "racket-tray"
     "racket-upnp"
+    "ellipsis-msg"
     ("simple-ini" #:version "0.3.3")
     "simple-log"
     "uuid"))

private-player-agent/player-agent-gui.rkt

@@ -9,6 +9,7 @@
          racket/string
          racket-tray
          simple-log
+         ellipsis-msg
          "player-agent-config.rkt"
          "player-agent-core.rkt"
          "player-agent-translate.rkt")
@@ -101,6 +102,9 @@
         (tray #f)
         (shutting-down? #f))
 
+    (define (cap200 msg)
+      (substring msg 0 (min 199 (string-length msg))))
+
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     ; goal   : Queue a status-label update in the GUI eventspace.
     ; pre    : message is a string supplied by the agent runtime.
@@ -114,7 +118,7 @@
       (queue-callback
        (λ ()
          (when status-message
-           (send status-message set-label message)))
+           (send status-message set-label (cap200 message))))
        #f))
 
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -206,6 +210,7 @@
                       "")))))
           (send playback-message
                 set-label
+                (cap200
                  (if track
                      (format "~a~a: ~a"
                              prefix
@@ -213,14 +218,15 @@
                                  (format " #~a" track-number)
                                  "")
                              track-label)
-                    (tr 'no-track)))
+                     (tr 'no-track))))
-          (send playback-details set-label (string-join details "  ·  "))
+          (send playback-details set-label (cap200 (string-join details "  ·  ")))
           (send playback-filename
                 set-label
+                (cap200
                  (if (and (string? filename)
                          (not (string=? filename "")))
                     filename
-                    "—")))))
+                    "—"))))))
 
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     ; goal   : Persist edited connection settings and reconnect the runtime.
@@ -246,7 +252,7 @@
         (save-player-agent-config! config)
         (send name-field set-value next-name)
         ((player-agent-runtime-reconnect! runtime) next-server next-name)
-        (send connect-button set-label (tr 'reconnect))))
+        (send connect-button set-label (cap200 (tr 'reconnect)))))
 
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     ; goal   : Release resources owned by the GUI agent exactly once.
@@ -322,7 +328,8 @@
             (new agent-frame%
                  (label (tr 'app-title))
                  (width 560)
-                 (height 310))))
+                 ;(height 310)
+                 )))
       (set! frame new-frame))
 
     (let* ((panel
@@ -347,6 +354,7 @@
                  (label (tr 'playback))
                  (alignment '(left top))
                  (stretchable-height #f)))
+           ;(msgs-pane (new vertical-pane% [parent panel]))
            (controls
             (new horizontal-panel%
                  (parent panel)
@@ -357,30 +365,31 @@
       ;; render their label and text poorly on some display configurations.
       (send (send id-field get-editor) lock #t)
       (set! playback-message
-            (new message%
+            (new ellipsis-msg%
                  (parent playback-panel)
                  (label (tr 'no-track))
-                 (auto-resize #t)))
+                 [ellipsis 'right] [auto-resize #t] [stretchable-width #t]
+                 ))
       (set! playback-details
-            (new message%
+            (new ellipsis-msg%
                  (parent playback-panel)
                  (label "00:00:00 / --:--:--")
-                 (auto-resize #t)))
+                 [ellipsis 'right] [auto-resize #t] [stretchable-width #t]))
       (set! playback-filename
-            (new message%
+            (new ellipsis-msg%
                  (parent playback-panel)
                  (label "—")
-                 (auto-resize #t)))
+                 [ellipsis 'right] [auto-resize #t] [stretchable-width #t]))
       (set! connect-button
             (new button%
                  (parent controls)
                  (label (tr 'save-connect))
                  (callback (λ (_button _event) (reconnect!)))))
       (set! status-message
-            (new message%
+            (new ellipsis-msg%
                  (parent controls)
                  (label (tr 'connecting))
-                 (auto-resize #t))))
+                 [ellipsis 'right] [auto-resize #t] [stretchable-width #t])))
 
     (set! playback-timer
           (new timer%
@@ -402,7 +411,7 @@
 
     (send frame show #t)
     ((player-agent-runtime-start! runtime))
-    (send connect-button set-label (tr 'reconnect))
+    (send connect-button set-label (cap200 (tr 'reconnect)))
     frame))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;