diff --git a/tp.el b/tp.el
index e16317f..1a2a10d 100644
--- a/tp.el
+++ b/tp.el
@@ -1093,36 +1093,20 @@ it will be applied to the text before updating."
                   (save-excursion
                     (tp--replace-reactive-text-in-buffer layer-name new-text props)))))))))))
 
-(defun tp--merge-props-with-base (base-props new-props)
-  "Merge NEW-PROPS into BASE-PROPS with NEW-PROPS taking precedence.
-Face properties are merged using `tp--merge-face-values', while other
-properties from NEW-PROPS override those in BASE-PROPS.  Properties only
-in BASE-PROPS are preserved.  Returns the merged plist, or nil if both
-arguments are nil."
-  (cond
-   ((null base-props) new-props)
-   ((null new-props) base-props)
-   (t
-    (let ((result (copy-sequence new-props)))
-      (cl-loop for (key val) on base-props by #'cddr
-               do (let ((new-val (plist-get result key)))
-                    (if (plist-member result key)
-                        ;; New props has this key - merge if face property
-                        (when (memq key '(face font-lock-face mouse-face))
-                          (setq result
-                                (plist-put result key
-                                           (tp--merge-face-values val new-val))))
-                      ;; New props doesn't have this key - add from base
-                      (setq result (plist-put result key val)))))
-      result))))
+(defvar tp-preserve-external-properties '(keymap mouse-face cursor pointer help-echo)
+  "List of text properties to preserve during reactive text updates.
+These properties are typically set by external libraries (like twidget's event
+system) and should not be overwritten when tp.el updates reactive text.
+Properties in this list will be preserved from the buffer during updates,
+while other properties will be replaced with the new values.")
 
 (defun tp--replace-reactive-text-in-buffer (layer-name new-text props)
   "Replace text in current buffer for reactive text with LAYER-NAME.
 NEW-TEXT is the new text to replace with.
 PROPS are the properties to apply to the new text.
-Text properties embedded in NEW-TEXT are merged with PROPS.
-All original text properties are preserved and merged with the new properties,
-with new properties taking precedence over original properties."
++Text properties embedded in NEW-TEXT are merged with PROPS.
++Properties listed in `tp-preserve-external-properties' that were applied
++by other libraries are preserved during the update."  
   (goto-char (point-min))
   (let ((match (text-property-search-forward 'tp-name layer-name t))
         ;; Merge embedded text properties from new-text into props
@@ -1131,21 +1115,28 @@ with new properties taking precedence over original properties."
       (let* ((m-start (prop-match-beginning match))
              (m-end (prop-match-end match))
              (old-text (buffer-substring-no-properties m-start m-end))
-             ;; Get ALL existing properties from the original text
+             ;; Preserve only specific external properties
              (existing-props (text-properties-at m-start))
-             ;; Merge: existing props as base, merged-props as new (takes precedence)
-             (final-props (tp--merge-props-with-base existing-props merged-props)))
-        (if (equal old-text (substring-no-properties new-text))
-            ;; Text content is the same, but properties may differ
-            ;; Use set-text-properties to replace with final properties
-            (set-text-properties m-start m-end final-props)
-          ;; Text content is different - delete old text and insert new
-          (delete-region m-start m-end)
-          (goto-char m-start)
-          (insert (substring-no-properties new-text))
-          ;; Apply final properties
-          (let ((new-end (+ m-start (length new-text))))
-            (set-text-properties m-start new-end final-props))))
+             (preserved-props nil))
+        ;; Extract only the explicitly listed external properties to preserve
+        (dolist (prop-name tp-preserve-external-properties)
+          (let ((val (plist-get existing-props prop-name)))
+            (when (and val (not (plist-member merged-props prop-name)))
+              (setq preserved-props
+                    (plist-put preserved-props prop-name val)))))
+        ;; Combine merged-props with preserved external props
+        (let ((final-props (append merged-props preserved-props)))
+          (if (equal old-text (substring-no-properties new-text))
+              ;; Text content is the same, but properties may differ
+              ;; Use set-text-properties to replace with final properties
+              (set-text-properties m-start m-end final-props)
+            ;; Text content is different - delete old text and insert new
+            (delete-region m-start m-end)
+            (goto-char m-start)
+            (insert (substring-no-properties new-text))
+            ;; Apply final properties
+            (let ((new-end (+ m-start (length new-text))))
+              (set-text-properties m-start new-end final-props)))))
       ;; Search for next match
       (setq match (text-property-search-forward 'tp-name layer-name t)))))