Refactor splash screen launch logic in Start.kt (#1357)

Simplifies the splash screen logic by removing coroutine delays and instead using a LaunchedEffect to trigger Base.main after the splash animation completes. The splash window now closes automatically when a new window is opened, improving startup flow and reliability.

app/src/processing/app/ui/Start.kt

@@ -14,10 +14,14 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.unit.dp
-import androidx.compose.ui.window.*
-import kotlinx.coroutines.delay
-import kotlinx.coroutines.launch
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.WindowPosition
+import androidx.compose.ui.window.application
+import androidx.compose.ui.window.rememberWindowState
 import processing.app.Base
+import java.awt.AWTEvent
+import java.awt.event.WindowEvent
+
 
 /**
  * Show a splash screen window. A rewrite of Splash.java
@@ -27,8 +31,6 @@ class Start {
         @JvmStatic
         fun main(args: Array<String>) {
             val duration = 200
-            val timeMargin = 50
-
             application {
                 var starting by remember { mutableStateOf(true) }
                 Window(
@@ -44,24 +46,10 @@ class Start {
                     )
                 ) {
                     var visible by remember { mutableStateOf(false) }
-                    val composition = rememberCoroutineScope()
+                    var launched by remember { mutableStateOf(false) }
                     LaunchedEffect(Unit) {
                         Toolkit.setIcon(window)
-
                         visible = true
-                        composition.launch {
-                            delay(duration.toLong() + timeMargin)
-                            try {
-                                Base.main(args)
-                            } catch (e: Exception) {
-                                throw InternalError("Failed to invoke main method", e)
-                            }
-                            composition.launch {
-                                visible = false
-                                delay(duration.toLong() + timeMargin)
-                                starting = false
-                            }
-                        }
                     }
                     AnimatedVisibility(
                         visible = visible,
@@ -76,8 +64,23 @@ class Start {
                                 durationMillis = duration,
                                 easing = LinearEasing
                             )
-                        )
+                        ),
                     ) {
+                        LaunchedEffect(visible, transition.currentState) {
+                            if (launched) return@LaunchedEffect
+                            if (!visible) return@LaunchedEffect
+                            // Wait until the view is no longer transitioning
+                            if (transition.targetState != transition.currentState) return@LaunchedEffect
+                            launched = true
+                            Base.main(args)
+                            // List for any new windows opening, and close the splash when one does
+                            java.awt.Toolkit.getDefaultToolkit()
+                                .addAWTEventListener({ event ->
+                                    if (event.id != WindowEvent.WINDOW_OPENED) return@addAWTEventListener
+
+                                    visible = false
+                                }, AWTEvent.WINDOW_EVENT_MASK);
+                        }
                         Image(
                             painter = painterResource("about-processing.svg"),
                             contentDescription = "About",