Schedule a redraw when resuming from suspension

Until now the repaint after fg was accidental: it only happened because
the suspend keybinding handler still had a flush pending on the UI
thread, and only if that flush happened to run after the SIGCONT
handler had re-engaged the screen. Now that flushes are skipped while
suspended, losing that race would leave the screen blank until the next
input event arrives, so schedule a redraw explicitly (#5309).

pkg/gocui/gui.go

@@ -1976,6 +1976,11 @@ func (g *Gui) Resume() error {
 
 	g.suspended = false
 
+	// Schedule a redraw of the whole screen. Nothing else guarantees one:
+	// flushes are skipped while suspended, and after re-engaging the screen
+	// the terminal shows nothing until we draw again.
+	go func() { g.gEvents <- GocuiEvent{Type: eventResize} }()
+
 	return nil
 }
 

pkg/gocui/suspend_test.go

@@ -64,9 +64,6 @@ func TestResumeSchedulesRedraw(t *testing.T) {
 	case <-time.After(100 * time.Millisecond):
 	}
 
-	/* EXPECTED:
 	assert.Equal(t, eventResize, ev.Type,
 		"resuming must schedule a redraw; without one the screen stays blank until the next event arrives")
-	ACTUAL: */
-	assert.Equal(t, eventNone, ev.Type)
 }