video: Add borderless fullscreen window mode by maininformer · Pull Request #1371 · omf2097/openomf

maininformer · 2026-04-07T06:30:34Z

Summary

Add a new borderless config option for borderless fullscreen (SDL_WINDOW_FULLSCREEN_DESKTOP)
fullscreen remains a bool — fully backward compatible with existing configs
In-game video menu gets a separate BORDERLESS ON/OFF toggle
Borderless fullscreen allows easy Alt-Tab/Cmd-Tab without hijacking the display

Config example

fullscreen=true
borderless=true

Test plan

fullscreen=false — game runs windowed
fullscreen=true, borderless=false — exclusive fullscreen (existing behavior)
fullscreen=true, borderless=true — borderless fullscreen, can Alt-Tab away
Old configs with just fullscreen=true still work (borderless defaults to false)
Toggle both options via in-game VIDEO settings menu

🤖 Generated with Claude Code

maininformer · 2026-04-07T06:37:56Z

Closing for now — still WIP. Will reopen when backward compatibility with fullscreen=true configs and menu alignment are addressed.

katajakasa · 2026-04-07T17:31:08Z


    if(fullscreen) {
-        if(SDL_SetWindowFullscreen(w, SDL_WINDOW_FULLSCREEN) != 0) {
+        Uint32 fs_flag = borderless ? SDL_WINDOW_FULLSCREEN_DESKTOP : SDL_WINDOW_FULLSCREEN;


We don't use the SDL int types.

katajakasa · 2026-04-07T17:32:29Z

    menu_attach(menu, textselector_create_bind_opts("FULLSCREEN", "Run the game in a fullscreen window.", NULL, NULL,
                                                    &setting->video.fullscreen, offon_opts, 2));
+    menu_attach(menu,
+                textselector_create_bind_opts("BORDERLESS", "Use borderless fullscreen for easy Alt-Tab switching.",


due to how little room we have in the UI, the fullscreen option should be multi-option toggleable. Also, the code could use enum for the variable type. To avoid compatibility issues, the option in configs should be called something new (e.g. window_mode or somesuch).

EDIT: clarified a bit

katajakasa · 2026-04-07T17:34:04Z

Note that since we now started receiving AI code PR's, we are currently considering the AI policy. This PR is probably going to have to wait until we have some idea how we want to handle them.

maininformer · 2026-04-09T01:26:34Z

Thank you.

Note that since we now started receiving AI code PR's, we are currently considering the AI policy. This PR is probably going to have to wait until we have some idea how we want to handle them.

This sounds good to me; please let me know if I can be of help.

I Will address the comments.

One question, should the borderless be the default behavior of fullscreen? Adding a new enum works. The issue is many players may not know what "borderless" means. Plus the word "borderless" is too long for the UI and mangles it. Can try shorter words but that would be even more mysterious.

katajakasa · 2026-04-09T08:54:09Z

Thank you.

Note that since we now started receiving AI code PR's, we are currently considering the AI policy. This PR is probably going to have to wait until we have some idea how we want to handle them.

This sounds good to me; please let me know if I can be of help.

I Will address the comments.

One question, should the borderless be the default behavior of fullscreen? Adding a new enum works. The issue is many players may not know what "borderless" means. Plus the word "borderless" is too long for the UI and mangles it. Can try shorter words but that would be even more mysterious.

I would just use:
FULLSCREEN: OFF
FULLSCREEN: WINDOWED
FULLSCREEN: EXCLUSIVE

and then explain the modes in description. If there is need to shorten, then "FULLSCREEN" can just be "FS" or "FS MODE" or somesuch (with description explanation).

katajakasa · 2026-04-11T16:29:30Z

+    WINDOW_MODE_WINDOWED,
+    WINDOW_MODE_BORDERLESS,
+    WINDOW_MODE_FULLSCREEN
+} window_mode;


there should also be a typedef for this, and that should be used as a function argument type, if possible.

katajakasa · 2026-04-11T16:30:04Z

Right, the AI policy is now at https://github.com/omf2097/openomf/blob/master/CONTRIBUTING.md#ai--coding-assistant-policy -- please check it out.

…ve fullscreen Replace the simple fullscreen toggle with a three-way window_mode enum (WINDOWED, BORDERLESS, FULLSCREEN). Borderless mode uses SDL_WINDOW_FULLSCREEN_DESKTOP for easy Alt-Tab switching without hijacking the display. Also replaces SDL Uint32 types with standard C types per project conventions. Assisted-by: Claude Code (Claude Opus 4.6)

maininformer · 2026-04-17T22:33:30Z

Addressed.

katajakasa · 2026-04-17T23:43:20Z

 }

-bool create_window(SDL_Window **window, int width, int height, bool fullscreen) {
+bool create_window(SDL_Window **window, int width, int height, int window_mode) {


You still need to use the new type. For example this would be "window_mode window_mode" instead of "int window_mode". Idea is that we declare by type that this variable can only contain the three types defined by the typedef. This goes for all functions where this is used.

Replace int with the window_mode enum typedef in all function signatures, function pointer typedefs, and local variables that hold window mode values. Assisted-by: Claude Code (Claude Opus 4.6)

maininformer · 2026-04-22T04:20:59Z

Updated to use the window_mode typedef instead of int in all function signatures, function pointer typedefs, and local variables. The settings_video struct field remains int because the GUI textselector widget binds to it as int *.

Also updated the commit trailers to use Assisted-by per the new AI policy.

Reformat two manually-broken multi-line constructs to satisfy the clang-format-18 style check that runs in CI. No semantic changes. Assisted-by: Claude Code (Claude Opus 4.7)

katajakasa · 2026-04-26T23:43:12Z

Issue: Switching to fullscreen exclusive seems to break 4:3 aspect ratio with black sides.

maininformer · 2026-04-30T05:47:05Z

@katajakasa cannot reproduce this. Could you please share an image? and is this behavior absent on master?

katajakasa · 2026-05-04T20:42:58Z

@katajakasa cannot reproduce this. Could you please share an image? and is this behavior absent on master?

Sorry, took me a while to get back to this. So after some poking, it seems that the fullscreen aspect ratio stuff is broken in master also. What /should/ happen is that when 4:3 is selected, and fullscreen is enabled (any fullscreen mode), and a 16:9 or 16:10 resolution is selected, there should be black bars in the right and the left of the screen. I think we can consider that a separate issue though.

Edit: Otherwise I think this seems fine now. One more squash so that things are in a single commit, and I think we can merge.

maininformer closed this Apr 7, 2026

maininformer reopened this Apr 7, 2026

katajakasa reviewed Apr 7, 2026

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katajakasa reviewed Apr 11, 2026

View reviewed changes

maininformer force-pushed the fullscreen-desktop-mode branch from ba44e26 to 8157369 Compare April 17, 2026 22:32

katajakasa reviewed Apr 17, 2026

View reviewed changes

video: Use window_mode typedef in function signatures

dcb80b2

Replace int with the window_mode enum typedef in all function signatures, function pointer typedefs, and local variables that hold window mode values. Assisted-by: Claude Code (Claude Opus 4.6)

video: Apply clang-format to menu_video.c

1bf1b60

Reformat two manually-broken multi-line constructs to satisfy the clang-format-18 style check that runs in CI. No semantic changes. Assisted-by: Claude Code (Claude Opus 4.7)

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Summary

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