Initial support for application specific overrides.

internal/app/screen_updates.go

@@ -58,8 +58,16 @@ func (a *application) read_screen() error {
 		}
 	}
 	a.clipboards.terminal = snapshot.Terminal
+	a.lastSnapshot = snapshot
+	frame, ready := a.observe_override(snapshot)
+	if !ready {
+		a.lastTerminal, a.lastActive = snapshot.Terminal, snapshot.Active
+		a.lastGeneration, a.lastRows, a.lastCols = snapshot.Generation, snapshot.Rows, snapshot.Cols
+		a.lastNumLock = snapshot.NumLock
+		return nil
+	}
 	updated := time.Now()
-	output := a.engine.Update(snapshot)
+	output := a.engine.Update_application(snapshot, frame)
 	if a.options.Spellcheck != nil && a.settings.live.Reading.Spellcheck && !a.ui.active && !a.muted && !a.temporarySilence {
 		for _, word := range a.engine.Completed_words() {
 			a.options.Spellcheck.Submit(spellcheck.Request{Operation: spellcheck.Automatic, Word: word, Generation: a.spellSession, Revision: a.spellFeedback})