08536: All: Numscreens 2 with -nowindow can show black screen

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08536	Core	Minor	Always	Dec 17, 2022, 02:47	Jan 14, 2023, 00:56

Tester	Robbbert	View Status	Public	Platform	MAME (Self-compiled)
Assigned To		Resolution	Won't fix	OS	Windows 10/11 (64-bit)
Status [?]	Closed			Driver
Version	0.250	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	08536: All: Numscreens 2 with -nowindow can show black screen
Description	Numscreens 2 with -nowindow can show black screen
Steps To Reproduce	I tested with pacman and mk14, but I suppose it could happen with any machine. >mame pacman -numscreens 2 -nowindow (d3d is default on windows) produces a totally black screen (screen 1 is presented by default). Alt-tabbing to screen 0 shows the game running; going back to screen 1 shows blackness. If I alt-enter to turn the screens into windows they both work fine. If I try various combinations it can error out, or screen 1 becomes mysteriously minimised, showing the desktop instead. Unable to create the Direct3D device (8876086C) Unable to initialize Direct3D 9 All video modes show the black screen at start, however alt-tabbing and alt-enter in random ways can produce weird results. For example opengl can end up with one screen at -nowindow with the other one at -window.
Additional Information	It regressed at either 0.227 or 0.228 .
Github Commit

Flags
Regression Version
Affected Sets / Systems	All

Attached Files

No.21006 Tafoid Administrator Jan 10, 2023, 10:46	Not entirely sure what is happening here. It used to only show 1 full screen if your system only had one display active while using numscreens larger than what is available. Now, it seems to be creating the windows (or screens), but since there is no path to display, the extra screens are showing black. My assessment anyway..
No.21010 cuavas Administrator Jan 12, 2023, 15:05	Do you actually have two physical monitors? If use fullscreen with -numscreens set to a larger number than your number of physical monitors, you get to keep the pieces when it breaks.
No.21011 Robbbert Moderator Jan 13, 2023, 03:29	Sounds like it's not guaranteed to work or it's unsupported, then. Closed.
No.21013 cuavas Administrator Jan 13, 2023, 13:35	I'll look at making it refuse to enter full screen if there aren't enough screens when I get around to cleaning up the interface between the render targrts and OSD layer.