Fixed issue #308

This commit also fixes a bug that caused the window to not maximize
correctly on a secondary monitor when ignoring the taskbar.
Update Flyout.cs
Merge pull request #430 from flagbug/issue-308-fix

Fixed issue #308
Merge pull request #432 from Traquina/patch-2

Update Flyout.cs
bugfix for issue raised in #435
Merge branch 'master' of github.com:MahApps/MahApps.Metro