From d922c3085a826c3cbf0620d3fc57008219a64419 Mon Sep 17 00:00:00 2001
From: Ilya Fedin <fedin-ilja2010@ya.ru>
Date: Fri, 16 Jul 2021 10:23:13 +0400
Subject: [PATCH 1/2] Don't inherit system font style

---
 ui/style/style_core_custom_font.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ui/style/style_core_custom_font.cpp b/ui/style/style_core_custom_font.cpp
index 570d169..825726f 100644
--- a/ui/style/style_core_custom_font.cpp
+++ b/ui/style/style_core_custom_font.cpp
@@ -8,6 +8,7 @@
 
 #include "ui/style/style_core_font.h"
 
+#include <QGuiApplication>
 #include <QFontDatabase>
 
 namespace style {
@@ -33,7 +34,7 @@ QFont ResolveFont(uint32 flags, int size) {
 	const auto &custom = bold ? BoldFont : RegularFont;
 	const auto useCustom = !custom.family.isEmpty();
 
-	auto result = QFont();
+	auto result = QFont(QGuiApplication::font().family());
 	if (flags & FontMonospace) {
 		result.setFamily(MonospaceFont());
 	} else if (useCustom) {

From 0ad1d2c9652e185dc8f5b07f90419babbd2416ab Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Sat, 17 Jul 2021 12:43:35 +0300
Subject: [PATCH 2/2] Check shader compiling/linking in detection.

---
 ui/gl/gl_detection.cpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/ui/gl/gl_detection.cpp b/ui/gl/gl_detection.cpp
index 195f2bc..10a47ed 100644
--- a/ui/gl/gl_detection.cpp
+++ b/ui/gl/gl_detection.cpp
@@ -6,6 +6,7 @@
 //
 #include "ui/gl/gl_detection.h"
 
+#include "ui/gl/gl_shader.h"
 #include "ui/integration.h"
 #include "base/debug_log.h"
 
@@ -87,6 +88,22 @@ Capabilities CheckCapabilities(QWidget *widget) {
 		LOG_ONCE(("OpenGL: Shaders not supported."));
 		return {};
 	}
+	{
+		auto program = QOpenGLShaderProgram();
+		LinkProgram(
+			&program,
+			VertexShader({
+				VertexViewportTransform(),
+				VertexPassTextureCoord(),
+			}),
+			FragmentShader({
+				FragmentSampleARGB32Texture(),
+			}));
+		if (!program.isLinked()) {
+			LOG_ONCE(("OpenGL: Could not link simple shader."));
+			return {};
+		}
+	}
 	const auto supported = context->format();
 	switch (supported.profile()) {
 	case QSurfaceFormat::NoProfile: {