Unity doesn't support _NET_WM_MOVERESIZE

Telegram/CMakeLists.txt

@@ -843,6 +843,7 @@ PRIVATE
     platform/linux/notifications_manager_linux.h
     platform/linux/specific_linux.cpp
     platform/linux/specific_linux.h
+    platform/linux/window_title_linux.h
     platform/mac/file_utilities_mac.mm
     platform/mac/file_utilities_mac.h
     platform/mac/launcher_mac.mm

Telegram/SourceFiles/platform/linux/window_title_linux.h

@@ -0,0 +1,43 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "platform/platform_window_title.h"
+#include "platform/linux/linux_desktop_environment.h"
+#include "base/object_ptr.h"
+
+namespace Window {
+namespace Theme {
+
+int DefaultPreviewTitleHeight();
+void DefaultPreviewWindowFramePaint(QImage &preview, const style::palette &palette, QRect body, int outerWidth);
+
+} // namespace Theme
+} // namespace Window
+
+namespace Platform {
+
+inline object_ptr<Window::TitleWidget> CreateTitleWidget(QWidget *parent) {
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) || defined DESKTOP_APP_QT_PATCHED
+	if (!DesktopEnvironment::IsUnity()) {
+		return object_ptr<Window::TitleWidgetQt>(parent);
+	}
+#endif // Qt >= 5.15 || DESKTOP_APP_QT_PATCHED
+
+	return { nullptr };
+}
+
+inline int PreviewTitleHeight() {
+	return Window::Theme::DefaultPreviewTitleHeight();
+}
+
+inline void PreviewWindowFramePaint(QImage &preview, const style::palette &palette, QRect body, int outerWidth) {
+	return Window::Theme::DefaultPreviewWindowFramePaint(preview, palette, body, outerWidth);
+}
+
+} // namespace Platform

Telegram/SourceFiles/platform/platform_window_title.h

@@ -27,7 +27,9 @@ void PreviewWindowFramePaint(QImage &preview, const style::palette &palette, QRe
 #include "platform/mac/window_title_mac.h"
 #elif defined Q_OS_WIN // Q_OS_MAC
 #include "platform/win/window_title_win.h"
-#else // Q_OS_MAC || Q_OS_WIN
+#elif defined Q_OS_UNIX // Q_OS_MAC || Q_OS_WIN
+#include "platform/linux/window_title_linux.h"
+#else // Q_OS_MAC || Q_OS_WIN || Q_OS_UNIX
 
 namespace Platform {
 
@@ -49,4 +51,4 @@ inline void PreviewWindowFramePaint(QImage &preview, const style::palette &palet
 
 } // namespace Platform
 
-#endif // Q_OS_MAC || Q_OS_WIN
+#endif // Q_OS_MAC || Q_OS_WIN || Q_OS_UNIX

Telegram/SourceFiles/ui/widgets/separate_panel.cpp

@@ -555,12 +555,15 @@ void SeparatePanel::mousePressEvent(QMouseEvent *e) {
 	if (e->button() == Qt::LeftButton) {
 		if (dragArea.contains(e->pos())) {
 #if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) || defined DESKTOP_APP_QT_PATCHED
-			windowHandle()->startSystemMove();
+			const auto dragViaSystem = windowHandle()->startSystemMove();
 #else // Qt >= 5.15 || DESKTOP_APP_QT_PATCHED
-			_dragging = true;
-			_dragStartMousePosition = e->globalPos();
-			_dragStartMyPosition = QPoint(x(), y());
+			const auto dragViaSystem = false;
 #endif // Qt < 5.15 && !DESKTOP_APP_QT_PATCHED
+			if (!dragViaSystem) {
+				_dragging = true;
+				_dragStartMousePosition = e->globalPos();
+				_dragStartMyPosition = QPoint(x(), y());
+			}
 		} else if (!rect().contains(e->pos()) && _hideOnDeactivate) {
 			LOG(("Export Info: Panel Hide On Click."));
 			hideGetDuration();
@@ -569,7 +572,6 @@ void SeparatePanel::mousePressEvent(QMouseEvent *e) {
 }
 
 void SeparatePanel::mouseMoveEvent(QMouseEvent *e) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0) && !defined DESKTOP_APP_QT_PATCHED
 	if (_dragging) {
 		if (!(e->buttons() & Qt::LeftButton)) {
 			_dragging = false;
@@ -578,15 +580,12 @@ void SeparatePanel::mouseMoveEvent(QMouseEvent *e) {
 				+ (e->globalPos() - _dragStartMousePosition));
 		}
 	}
-#endif // Qt < 5.15 && !DESKTOP_APP_QT_PATCHED
 }
 
 void SeparatePanel::mouseReleaseEvent(QMouseEvent *e) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0) && !defined DESKTOP_APP_QT_PATCHED
-	if (e->button() == Qt::LeftButton) {
+	if (e->button() == Qt::LeftButton && _dragging) {
 		_dragging = false;
 	}
-#endif // Qt < 5.15 && !DESKTOP_APP_QT_PATCHED
 }
 
 void SeparatePanel::leaveEventHook(QEvent *e) {

Telegram/SourceFiles/ui/widgets/separate_panel.h

@@ -93,11 +93,9 @@ private:
 	bool _useTransparency = true;
 	style::margins _padding;
 
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0) && !defined DESKTOP_APP_QT_PATCHED
 	bool _dragging = false;
 	QPoint _dragStartMousePosition;
 	QPoint _dragStartMyPosition;
-#endif // Qt < 5.15 && !DESKTOP_APP_QT_PATCHED
 
 	Ui::Animations::Simple _titleLeft;
 	bool _visible = false;