Multiple check for updates calls when existing window is open does not load release notes

[johnmurphy01]

When a check for updates dialog UI is already open and subsequent check for updates occur while the dialog UI is still open results in the release notes text not loading. This is in the case that release notes are loaded from the <description> tag.

Steps to reproduce:

• Launch application
• Invoke WinSparkle so that a new update UI is present
• Manually check for updates while the UI is open Observe that the release notes text area has no content.

First update check:

Next update check with the WinSparkle window still open:

I believe this is due to the web browser already being loaded and so there is some initialization that needs to take place but is getting skipped. I will make my proposed modification and submit a PR.

[johnmurphy01]

https://github.com/vslavik/winsparkle/pull/156

Thanks!

[vslavik]

"Backporting" important update from #156 (feel free to create PRs right away without corresponding issue, BTW):

Added Note: This issue does appear to only affect release notes that are loaded using the description tag. Loading release notes using a url does not appear to have this issue.