Enabling fullscreen via code shows window border at screen edges (DisplayServer regression)

[RedMser]

---

Bugsquad note: This issue has been confirmed several times already. No need to confirm it further.

---

Godot version

4.0.dev (835da44)

System information

Windows 10, Vulkan Clustered, 3 monitor setup

Issue description

When changing fullscreen mode via code, the window's border is visible at the edges of the screen. This does not happen when enabling the fullscreen project setting instead.

Launching the MRP with a high contrast theme (where window borders are white) with x10 zoom on the top left corner of my screen:

When using the default Windows 10 theme:

This confirms that you see the window's borders.

Steps to reproduce

Create a fresh project. Then either in _ready, or when pressing a key, run:

get_tree().root.mode = Window.MODE_FULLSCREEN
# This does not help:
#get_tree().root.borderless = true

Minimal reproduction project

win_fullscreen_border.zip

[Sch1nken]

I just tested the example and for me on Win10 the Taskbar is also visible (window seems to be behind the Taskbar)

[TokisanGames]

I've noticed this on my system w/ Windows 11, Vulkan, RTX3070 and GD4a14. Dual monitor set up (1920x1200, 1920x1080). It exists on all games, including the editor. It's not just via code. It is the window mode set by DisplayServer.

The title of this ticket should be changed to something like Border on Full Screen.

DisplayServer.WINDOW_MODE_FULLSCREEN results in a 1px wide border in games and the editor when in full screen mode (Shift+11).

DisplayServer.WINDOW_MODE_EXCLUSIVE_FULLSCREEN removes the border.

I can fix it for my game, but I don't see an option to change the editor to exclusive mode. Its hard to see in a screenshot, so I added black borders around so you can see the white border.

[steelywing]

And the border cannot trigger mouse click event

[vpellen]

For what it's worth, you can actually get around this and achieve "true" borderless fullscreen by setting the window mode to a standard window (i.e. not maximized or minimized, not borderless, not unresizable), changing its size to your screen resolution, and setting its position to the monitor position (which is going to be 0,0 if you have only one monitor). It'll take up the full screen without triggering exclusive mode. Sometimes it leaves behind the taskbar and you have to alt tab a couple of times, but I find that's an issue with windows on multiple games anyway.

I have a hunch that's just how windows handles borderless fullscreen - if a window has a position and size equal to a monitor, it'll just fullscreen on that monitor. Enabling settings such as windowless or non-resizable actually stops this fix from working, though I don't know how much of that is windows getting confused and how much of it is Godot trying to be clever with your settings and doing the wrong thing by mistake.

Incidentally, exclusive fullscreen introduces a delay on mouse movements, which is quite frustrating if you've got an object tracking the mouse.