BUG: MessageBoxEx (e.g. Plugin Install Popup) doesn't handle closing correctly

### Checks

- [x] I have checked that this issue has not already been reported.

- [x] I am using the latest version of Flow Launcher.

- [x] I am using the prerelease version of Flow Launcher.

### Problem Description

The MessageBoxEx window (which is spawned for example when installing a plugin) has an x button that doesn't work, and treats force closes as accepts instead of cancels
It seems to me that anything other than clicking "yes" should be treated as "no".

### To Reproduce

1. Try to install a plugin from the plugin store or plugin manager
2. Try to click on the x button - nothing will hapen
3. Press alt+f4 or right click on the title bar and select close - it will treat that as an accept instead of a cancel

### Screenshots

### Flow Launcher Version

2.1.2

### Windows Build Number

10.0.26200.8524

### Error Log