Restore cursor shape on exit. (#793) (#794)

Fixed: https://github.com/ArthurSonzogni/FTXUI/issues/792

src/ftxui/component/button.cpp

@@ -124,7 +124,8 @@ class ButtonBase : public ComponentBase, public ButtonOption {
       return false;
     }
 
-    if (event.mouse().IsPressed()) {
+    if (event.mouse().button == Mouse::Left &&
+        event.mouse().motion == Mouse::Pressed) {
       TakeFocus();
       OnClick();
       return true;