bug(windows) open Keyman config while Keyman config is in the middle of something

**Describe the bug**
While multitasking, I had Keyman Configuration opened and about to download a keyboard from there using "Download keyboards..."; but then I was distracted by something else mid way. I then when away and work on something else (say, writing a bug report :) ).

After a while, I am back to Configuration, but without going to the existing "Download keyboard..." window, I instead open Keyman Configuration again. From the new configuration window, there is a warning sound and flashing screen each time I clicked on the configuration window.

In order to get our of that I have to go to a separate app (any app), then come back to Keyman Configuration to see the "Download keyboard..." window.

**Expected behavior**
The "Download keyboard..." window should be shown up once Keyman Configuration is triggered while the "Download keyboard..." window is active.

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**Keyman Desktop:**
- OS: Windows 10 Pro 1909
- Keyman version: 13.0.115
- Target Application: [self]