WIP: The Avalonia port

[luizzeroxis]

Downloads:

• macOS
• Linux
• Windows

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STATUS: You can view almost everything in a data file, but editing might not be possible for some properties. Scripts are hit or miss.

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I've been working on the Avalonia port of UndertaleModTool for a little while, so I decided to finally make a draft PR for it, in case anyone else wants to help. As discussed in #460 and elsewhere, Avalonia is probably the best choice, since it's multi-platform, works in C# and seems to suck less than alternatives. I tested the current build on Linux and it seems to work fine (except the performance).

Currently, I'm working on making it work as a sort of 'view only' UTMT, so those not on Windows can datamine games, at least. Of course, the architecture still has to be made such that we could later add editing functionality.

But, it is not complete yet. No, it is far from complete. Here's a TODO list of all the things I can think of that need to be done (but there's certainly more):

• General

  • Open data file
  • Save data file
    • Save debug information
  • Temp run
  • Sub data files (like audiogroups)
  • Middle click to open in new tab
  • Keyboard shortcuts
  • Make sure null and non-existent items work

• Main UI

  • Tree view
    • Filter by name
    • Virtualization
    • Right click menu
    • Reorder resources
  • Tabs
    • Back/forward navigation
    • Open in the same tab
    • Keep tab state
  • Resource ID number

• Editors

  • General info editor
  • Global init scripts editor
  • Game end scripts editor
  • Audio group editor
  • Sound editor
    • Play audio
    • Deal with audio groups
  • Sprite editor
    • Show first image initially
  • Background editor
  • Path editor
    • Render path
  • Script editor
  • Shader editor
  • Font editor
    • Glyph editor
  • Timeline editor
  • Game object editor
  • Room editor
    • Background properties
    • View properties
    • Instance properties
    • Tile properties
    • Layer properties
    • Render all items
    • Edit all items
    • Select and move items
    • Scale and rotate items
    • Tiles layer editing
    • Save to image
    • Reorder items
    • Copy and paste items
    • Gray out disabled items
  • Extension editor
    • Product ID
  • Texture page item editor
    • Show item in texture
  • Code editor
    • Syntax highlighting
    • Parent entry
    • Right click stuff
  • Variable editor
  • Function editor
  • Code local editor
  • String editor
  • Embedded texture editor
    • Click item to open
  • Embedded audio editor
  • Texture group information editor
  • Embedded image editor
  • Particle system editor
  • Particle system emitter editor

• Controls

  • String reference box
    • Choose to replace one/all
  • Resource reference box
  • Flags box
    • Text box
  • Editable data grid
  • Color picker
  • Image viewer

• Other

  • Basic message dialogs
  • Text input dialog
  • Loader dialog
  • Settings
    • All settings
  • Search in code
  • Find references
  • File associations
  • Icon

• Scripting

  • Be able run scripts
  • Command textbox
  • Full scripting API

• Project

  • Open/save projects
  • View unexported assets window
  • View and edit code entry GML
  • Auto mark for export when editing resources

[github-actions]

Download the artifacts for this pull request here:

GUI:

• GUI-windows-latest-isBundled-false-isSingleFile-false
• GUI-windows-latest-isBundled-false-isSingleFile-true

CLI:

• CLI-windows-latest-isBundled-false
• CLI-macOS-latest-isBundled-false
• CLI-ubuntu-latest-isBundled-false

[5GameMaker]

BUG: After opening a new file, search is not applied until it's modified

[CST1229]

random thing i found: middle-clicking or ctrl+clicking numbers in code doesnt seem to work in this version (unlike in the current main version), only rightclicking
(similar for functions/assets, where only middle click works and not ctrl+click)

[CST1229]

also, ctrl+s always shows the save dialog at the home directory with nothing selected (instead of immediately saving the data file to its last location if one was loaded), at least for me

[ephoton]

On macOS, keyboard shortcuts should use Cmd instead of Ctrl

[sjl057]

i'm getting really bad lag when trying to display a lot of text in scripts. for what it's worth, i have a high dpi monitor

[devek1]

I got an instant error on trying to launch the app from KDE Dolphin file manager:
The desktop entry file /home/devek1/GamingTools/UTMT Native/UndertaleModToolAvalonia.Desktop has no Type=... entry.

In order to fix this, the file has to simply be renamed with an appropriate extension, such as .x86-64 (or alternatively, removing the extension entirely), so that it is correctly opened as a binary rather than a desktop file.

[sjl057]

The package on the AUR also doesn't pass the validity check

…

On Fri, Jun 5, 2026 at 11:55 AM devek1 ***@***.***> wrote: *devek1* left a comment (UnderminersTeam/UndertaleModTool#2126) <#2126 (comment)> I got an instant error on trying to launch the app from KDE Dolphin file manager: The desktop entry file /home/devek1/GamingTools/UTMT Native/UndertaleModToolAvalonia.Desktop has no Type=... entry. In order to fix this, the file has to simply be renamed with an appropriate extension, such as .x86-64 (or alternatively, removing the extension entirely), so that it is correctly opened as a binary rather than a desktop file. — Reply to this email directly, view it on GitHub <#2126?email_source=notifications&email_token=AB6WUF6GET5O7Z44PMFF2JT46L3RVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRTGM3DQNZTGQYKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4633687340>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB6WUFYYFSDSHXM4BUMSD3D46L3RVAVCNFSM6AAAAAB5L5ISASVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DMMZTGY4DOMZUGA> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AB6WUF2G5P6F6UYFYA4BYRD46L3RVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRTGM3DQNZTGQYKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/AB6WUFZ22NOUWNN57X6ZIJT46L3RVA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRTGM3DQNZTGQYKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[Damglador]

AUR comment section would be a better place to report that. The package shouldn't have a validity check in the first place, so I've already sent a patch to fix that there.