fix multiplayer loading screen

app/src/main/java/gui/widget/SudokuSelector.java

@@ -39,6 +39,8 @@ public class SudokuSelector {
 
 	private final SmoothProgressBar genProgressBar;
 
+	private volatile boolean genDone = false;
+
 	public SudokuSelector(boolean canGenEmptyGrid, String confirmMessage) {
 		this.canGenEmptyGrid = canGenEmptyGrid;
 		this.confirmMessage = confirmMessage;
@@ -74,6 +76,8 @@ public class SudokuSelector {
 			int filled = this.doku.getFilledCells().size();
 			int total = this.doku.getCells().size();
 			this.genProgressBar.render(filled / (float) total);
+			if (genDone)
+				ImGui.closeCurrentPopup();
 			ImGui.endPopup();
 		} else {
 			stopGenThread();
@@ -82,12 +86,14 @@ public class SudokuSelector {
 
 	private void selectSudoku(MultiDoku doku, boolean empty) {
 		this.doku = doku;
+		this.genDone = false;
 		ImGui.openPopup("genProgress");
 		this.genThread = new Thread(() -> {
 			try {
 				if (!empty) {
 					SudokuFactory.fillDoku(doku, Difficulty.values()[difficulty.get()]);
 				}
+				this.genDone = true;
 				this.onSelect.emit(this.doku);
 			} catch (Exception e) {
 				e.printStackTrace();