Fix #1881: a Ctrl/Cmd drag while typing keeps what was typed

With the Type tool editing, a press with Ctrl (Cmd on the Mac) lends the
Selection tool for the drag. Its drag joined the open typing session, so its
preview started from the document before the typing: the type moved or
scaled and lost what had just been typed. The typing is now kept as its own
undo step before the lent tool takes the press, as Undo already does, and
typing goes on after the drag.

crates/engine/src/tooling.rs

@@ -115,6 +115,12 @@ impl Session {
             return *ev;
         }
         let Some(id) = self.lent_tool(self.tool.id()) else { return *ev };
+        // Typing in progress is kept as its own step first: the lent tool's drag previews from the
+        // document its interaction started from, which would drop the typing (#1881).
+        if crate::cmd::typing_in_progress(self) {
+            // Fails only without a document, and then there is no typing to keep.
+            let _ = crate::cmd::settle_interaction(self);
+        }
         let lent = self.make_tool(id);
         self.lender = Some(std::mem::replace(&mut self.tool, lent));
         PointerEvent { mods: Mods { cmd: false, ..ev.mods }, ..*ev }