Popup window doesn't display until chosen from windowlist

I’m having a problem with one application, where popup dialog windows don’t initially display. The program is Liferea, v. 1.10.3. I’m running Linux Mint 17.3 Mate edition.

What happens is that any dialog window is initially not displayed. For example, right click on a news feed, and select ‘Properties’, or select ‘About’ from the help menu. The window would seem to be present, because it shows up in Fvwm’s WindowList menu, and when selected from that menu, it then displays. But there is no icon for it showing up in FvwmIconMan, and if, prior to using WindowList, I drag the main Liferea window so that’s it’s mostly off the screen, the popup window is not visible. In the WindowList, the geometry attributes are such that it is not getting a +X+Y making it display outside of the display port.

I have no idea what to look for here. About all I can say is that this started happening after I did some modernizing of my Fvwm config. But I did no functional changes, just some color and icon changes, 1 use of colorsets and MultiPixMap in the active title and title buttons, and a some content changes for FvwmButtons.

Here’s what xwininfo tells me about one of these windows:

[code]xwininfo: Window id: 0x28062a7 “Subscription Properties”

Absolute upper-left X: 161
Absolute upper-left Y: 596
Relative upper-left X: 0
Relative upper-left Y: 0
Width: 640
Height: 408
Depth: 24
Visual: 0x20
Visual Class: TrueColor
Border width: 0
Class: InputOutput
Colormap: 0x22 (installed)
Bit Gravity State: NorthWestGravity
Window Gravity State: NorthWestGravity
Backing Store State: NotUseful
Save Under State: no
Map State: IsViewable
Override Redirect State: no
Corners: +161+596 -479+596 -479-20 +161-20
-geometry 640x408+158-17[/code]

Here’s the output from FvwmIdent for the “About” popup.

https://kek.gg/i/3B6tgQ.png

Any suggestions?

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