Defer launch warnings until after launch validation

We need to destroy the SDL window before we can be sure that Qt
can draw to the screen if we used KMSDRM.

app/streaming/session.cpp

@@ -902,27 +902,35 @@ bool Session::initialize()
         return false;
     }
 
+    // Display launch warnings in Qt only after destroying SDL's window.
+    // This avoids conflicts between the windows on display subsystems
+    // such as KMSDRM that only support a single window.
+    for (const auto &text : m_LaunchWarnings) {
+        // Emit the warning to the UI
+        emit displayLaunchWarning(text);
+
+        // Wait a little bit so the user can actually read what we just said.
+        // This wait is a little longer than the actual toast timeout (3 seconds)
+        // to allow it to transition off the screen before continuing.
+        uint32_t start = SDL_GetTicks();
+        while (!SDL_TICKS_PASSED(SDL_GetTicks(), start + 3500)) {
+            SDL_Delay(5);
+
+            if (!m_ThreadedExec) {
+                // Pump the UI loop while we wait if we're on the main thread
+                QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
+                QCoreApplication::sendPostedEvents();
+            }
+        }
+    }
+
     return true;
 }
 
 void Session::emitLaunchWarning(QString text)
 {
-    // Emit the warning to the UI
-    emit displayLaunchWarning(text);
-
-    // Wait a little bit so the user can actually read what we just said.
-    // This wait is a little longer than the actual toast timeout (3 seconds)
-    // to allow it to transition off the screen before continuing.
-    uint32_t start = SDL_GetTicks();
-    while (!SDL_TICKS_PASSED(SDL_GetTicks(), start + 3500)) {
-        SDL_Delay(5);
-
-        if (!m_ThreadedExec) {
-            // Pump the UI loop while we wait if we're on the main thread
-            QCoreApplication::processEvents(QEventLoop::ExcludeUserInputEvents);
-            QCoreApplication::sendPostedEvents();
-        }
-    }
+    // Queue this launch warning to be displayed after validation
+    m_LaunchWarnings.append(text);
 }
 
 bool Session::validateLaunch(SDL_Window* testWindow)

app/streaming/session.h

@@ -260,6 +260,7 @@ private:
     SdlInputHandler* m_InputHandler;
     int m_MouseEmulationRefCount;
     int m_FlushingWindowEventsRef;
+    QList<QString> m_LaunchWarnings;
 
     bool m_AsyncConnectionSuccess;
     int m_PortTestResults;