I was unable to decipher the State.pmj file, so I've been using Pmail in full screen mode.  Then today, just for yucks, I clicked the restore button in the Pegasus window and guess what - the window restored to its proper smaller size.  So, everything is back the way it should be.

 Thanks for all the help. 

Recently, when I start Pegasus Mail, the app window does not display.  The small app startup window displays with the version number and then, when it disappears, there is nothing on the screen.  The app does show on the Windows status line and it also appears in the Task Manager, where it shows very low CPU usage.  I believe that the app is actually running, since I periodically hear the sound indicating new mail received.  I just can't see it, so I can't do anything.

When I look at the installed apps listing in the Windows Apps & Features listing, I see 3 Pegasus entries -

Pegasus Mail v4.73 41.2 MB

Pegasus Mail HTML Renderer v2.4.9.9 4.64 MB

Pegasus Mail (no version) (no size)

I wonder what that last entry is.  Is that what's causing this problem? 

 I am running Windows 10. 

I can think of a couple things that would produce such behavior. One is if you used Pegasus Mail in a two (or more) display and its main windows was moved to the extended display and closed there. Does it rings a bell? You can check your display settings in Windows Control Panel. If you were using an extended display reverting it to the main display shall bring off borders applications to the main display, at least this is what happens here when I unplug my second display. Fingers crossed.

Indications are that Pegasus Mail is running.  Euler is probably correct about the main Pegasus Mail window being open off-screen.  Try right-clicking on the Windows taskbar and then selecting one of the window positioning options like "Cascade windows" or "Show windows stacked".  It's probably best to do this with all other programs closed.

Thanks, Euler.

But I use a laptop with a single external display connected.  The laptop display is not used.

Thanks, Brian.

 I tried clicking on the Windows taskbar and then selected each "Cascade windows" or "Show windows stacked" or "Show windows side by side".  None of them seem to do anything to the display layout.  What am I doing wrong?

Is Pegasus Mail minimized and hidden in the Notification area?

There is a caret symbol in the Windows taskbar just to the left of the date/time.  A hover over it with display "Show hidden icons".  These are the hidden Notification icons.

[quote user="HTR"]

Thanks, Euler.

But I use a laptop with a single external display connected.  The laptop display is not used.

[/quote]

OK, but it is important to know which monitor is assigned (Control Panel > Display Change > display settings) as the active one. If you change to your laptop display, or if you disconnect your external display, does it change anything?

This is weird.  I have the exact same issue today.   I came to the forum expecting to search through years worth of posts looking for clues, and it's the top issue!

 So on mine, it's basically like the Pegasus Mail window is permanently minimised.  Cascade Windows or Show windows stacked still fails to show the Pegasus window.

 I can Alt-Tab to Pegasus Mail (or click on its tab in the Windows Task Bar) and then it becomes the Active application in Windows.  When it is active I can use all the usual menu shortcuts (for example, Alt-F for the File menu), and I see the menus drawn in the top left of the screen and I can menu choose commands, and the commands appear to be doing things.  Only I never see the underlying program window and never see my mail folders etc. 

---

In my case, all this is on a laptop using only its built-in (default) single display.  Windows 10, nothing too strange.  Pegasus worked 100% OK last month and yesterday and this morning.   I didn't change any PC settings...

I do Alt-Tab between applications plenty, and in the past I have noticed that Pegasus can become flaky if the user attempts to Alt-Tab to it while it is in the middle of a POP3 fetching operation.  (I think this is because the POP3 fetching is not multi-threaded, as I've mentioned before, so the application locks for a long time during the fetch.)

 ---

 More info: using menu commands, I can open Pegasus Mail Help System but this has the same symptoms: nothing is visible except for its tab in the Task Bar, it's like it is permanently minimised or a size 0 window. 

OK so I've fixed it:

in Windows, after clicking on the Pegasus Mail tab to activate it, click Alt Space and then X for "Maximise".

For me at least, this restored the Pegasus Mail window to something visible, though my folders within Pegasus were all in strange new positions... 

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Some more testing shows that (in Windows 10) you can fairly easily push Pegasus into this state if you accidentally click the Windows key + the Down arrow key  (that's a shortcut for minimise).

The difference between Pegasus and other apps is that other apps restore themselves to the previous state if you then click Windows + Up arrow (or click on the app's tab in the Task Bar) but Pegasus doesn't respond to that - Pegasus does not have the "Restore" functionality for an app window in Windows 10.  (Restore is actually greyed out in the Alt Space menu for Pegasus).

Something for David's Windows 10 "todo" list hopefully?

Great fix!

 I tried it and it made the app window visible.  But, as you found, the windows within Pegasus are all in strange positions.  I have put them back in their (mostly) correct positions (for my setup) in the maximized window.  But how can I "Restore" Pegasus to the original size window that I had before this happened.  I don't want a maximized window but when I hit the Restore button in the upper right corner of the Pegasus app window, the app disappears again.

 My guess is that the coordinates of the app window corners are corrupted.  Are they kept somewhere within the Pegasus configuration files?

[quote user="HTR"]

Great fix!

 I tried it and it made the app window visible.  But, as you found, the windows within Pegasus are all in strange positions.  I have put them back in their (mostly) correct positions (for my setup) in the maximized window.  But how can I "Restore" Pegasus to the original size window that I had before this happened.  I don't want a maximized window but when I hit the Restore button in the upper right corner of the Pegasus app window, the app disappears again.

 My guess is that the coordinates of the app window corners are corrupted.  Are they kept somewhere within the Pegasus configuration files?

[/quote]

Windows' coordinates and sizes are kept into STATE.PMJ. It is not a file of easy hacking, quite au contraire. Shutdown Pegasus Mail and SAVE A COPY of STATE.PMJ first. Then look at it after those lines that appear to be out of context, things like coordinates with negative values, missing keys, missing values, incomplete values, etc. This file uses .INI architecture. Comment those lines or remove them. Then run Pmail and see what happens.

A great tool to use here is WinMerge. Use it to compare the "new" STATE.PMJ with the saved copy and you will be able to spot differences.