Is there a way to set the background color of the native win

Question

Is there a way to set the background color of the native window before content is rendered There s a white flash before the app s dark content appears All of the answers I saw for this were specific to Android

David W · Answer

I even tried making the window not visible for a second to let the content render but it still flashed white on making it visible perhaps content doesn t render while it s invisible

Thomas · Answer

Hey I was wondering did you find a good solution for this

David W · Answer

Nope it s on my wait and see pile for Compose slightly smiling face

Thomas · Answer

Yeah I am trying to fix a few things from that pile

Thomas · Answer

The JetBrains Toolbox app does not flash white so it should be possible

David W · Answer

No it is transparent but with the OS frame until everything is drawn then it appears

David W · Answer

good point

Thomas · Answer

Found the issue you can set the background color in the Window content using `window background =` but at that point the window is already shown so its too late

Thomas · Answer

Fix is to call it immediately after the ComposeWindow creation which is a bit difficult <https cs android com androidx platform frameworks support + androidx main compose ui ui src desktopMain kotlin androidx compose ui window Window desktop kt l=148 drc=c5559f4d2522a059fda3ea5c1d3a7ed6d6e7257c|https cs android com androidx platform frameworks support + androidx main compose desktop kt l=148 drc=c5559f4d2522a059fda3ea5c1d3a7ed6d6e7257c>

Thomas · Answer

The line I linked is where you need to call `this window background = ` which works

Thomas · Answer

ComposeWindow is actually a JFrame which has a default background color

Thomas · Answer

Calling the following before creating a window also works but not sure what it all affects ```javax swing UIManager getDefaults apply put control javax swing plaf ColorUIResource java awt Color RED ```

Thomas · Answer

I am now using the following workaround Call it just before the Window function ``` Composable private fun fixWhiteFlashOnStartup val background = MaterialTheme colors background remember background UIManager getDefaults apply put control ColorUIResource background toArgb ```

David W · Answer

interestingly i m still getting the flash

David W · Answer

I got it after trying ```javax swing UIManager getDefaults apply put control javax swing plaf ColorUIResource java awt Color RED ``` too

Thomas · Answer

Did you call that before Window onCloseRequest

Thomas · Answer

It works for me on macOS

David W · Answer

Windows here

Thomas · Answer

Hmm maybe this trick does not work on Windows will have to try that

Thomas · Answer

FYI there is a fix here <https github com JetBrains androidx pull 182>

David W · Answer

thank you you re the best