Paste pictures: Mod+Shift+V (Paste Formatting) no longer pastes a clipboard picture

The key-release fallback that pastes the system clipboard's picture treated every Mod+V release as
Paste. It now requires plain Mod+V or the Paste key (no Shift, no Alt), with a unit test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ui-egui/src/keys.rs

@@ -133,6 +133,13 @@ fn equation_key(app: &mut WordApp, key: Key, m: Modifiers) -> bool {
     true
 }
 
+/// Whether releasing `key` with `modifiers` is the plain Paste shortcut (Mod+V or the Paste
+/// key) — not Mod+Shift+V (Paste Formatting) or Mod+Alt+V (Paste Special) — so a clipboard
+/// picture may be pasted on it (#45).
+fn is_paste_release(key: Key, modifiers: egui::Modifiers) -> bool {
+    (modifiers.command || key == Key::Paste) && !modifiers.alt && !modifiers.shift
+}
+
 /// Events for the focused canvas: text, editing keys, clipboard, IME. While keytips are showing
 /// every key belongs to them (letters pick badges, Escape cancels), so nothing here runs.
 pub fn canvas_events(app: &mut WordApp, ctx: &egui::Context) {
@@ -152,7 +159,7 @@ pub fn canvas_events(app: &mut WordApp, ctx: &egui::Context) {
         // release; paste the clipboard's picture then (#45). A paste event before the release
         // means it was text. (The web reads pasted pictures itself.)
         if let egui::Event::Key { key: key @ (Key::V | Key::Paste), pressed: false, modifiers, .. } = &e {
-            let paste_keys = (modifiers.command || *key == Key::Paste) && !modifiers.alt;
+            let paste_keys = is_paste_release(*key, *modifiers);
             let pasted = std::mem::take(&mut app.canvas.pasted);
             if !pasted && paste_keys && app.session.math.is_none() && app.services.clipboard_picture.is_some() {
                 let _ = app.run("edit.paste", json!({}));
@@ -265,3 +272,18 @@ pub fn global_shortcuts(app: &mut WordApp, ctx: &egui::Context) {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn only_plain_paste_releases_paste_a_clipboard_picture() {
+        let m = |command, shift, alt| egui::Modifiers { command, shift, alt, ..Default::default() };
+        assert!(is_paste_release(Key::V, m(true, false, false)), "Mod+V");
+        assert!(is_paste_release(Key::Paste, m(false, false, false)), "the Paste key");
+        assert!(!is_paste_release(Key::V, m(true, true, false)), "Mod+Shift+V is Paste Formatting");
+        assert!(!is_paste_release(Key::V, m(true, false, true)), "Mod+Alt+V is Paste Special");
+        assert!(!is_paste_release(Key::V, m(false, false, false)), "a plain V");
+    }
+}