Dropdown menu doesn't change style properly in widgets example

[arctic-alpaca]

Describe the bug Clicking on the dropdown menu in the widgets example and then changing style with the toggler on the bottom left doesn't change the style of the dropdown menu. It only changes after clicking on it or after changing style twice again. Leaving the dropdown menu open when changing style results in one correct change when the menu collapses but then it doesn't change properly at the next change.

To Reproduce Steps to reproduce the behavior:

1. git clone https://github.com/redox-os/orbtk.git
2. cd orbtk
3. cargo run --example widgets --release
4. press on the dropdown menu
5. toggle a style change

Expected behavior The menu changes style with the rest of the window.

Screenshots

Desktop (please complete the following information):

• OS: Win10 1909

[learning]

The same on macOS 11.0.1, and after some clicks of dropdown menu & toggle theme, the interface nealy broken, mouse click not respond on most widgets.