corrected project manager popup, fixes #1721

tools/editor/project_manager.cpp

@@ -639,7 +639,7 @@ void ProjectManager::_open_project() {
 
 	if (selected_list.size()>1) {
 		multi_open_ask->set_text("Are you sure to open more than one projects?");
-		multi_open_ask->popup_centered(Size2(300,100));
+		multi_open_ask->popup_centered_minsize();
 	} else {
 		_open_project_confirm();
 	}
@@ -679,7 +679,7 @@ void ProjectManager::_run_project() {
 
 	if (selected_list.size()>1) {
 		multi_run_ask->set_text("Are you sure to run more than one projects?");
-		multi_run_ask->popup_centered(Size2(300,100));
+		multi_run_ask->popup_centered_minsize();
 	} else {
 		_run_project_confirm();
 	}
@@ -779,7 +779,7 @@ void ProjectManager::_erase_project()  {
 
 
 	erase_ask->set_text("Erase project from list?? (Folder contents will not be modified)");
-	erase_ask->popup_centered(Size2(300,100));
+	erase_ask->popup_centered_minsize();
 
 }