Add message formatting help beside Join with a fenced code example

tools/chatgui/src/channellist.cpp

@@ -20,6 +20,7 @@
 #include <QUrl>
 #include <QSignalBlocker>
 #include <QToolTip>
+#include <QMessageBox>
 
 extern "C" {
 #include "../../lib/debug_config.h"
@@ -281,6 +282,29 @@ ChannelList::ChannelList(DbManager* db, QWidget *parent)
     plusBtn->setStyleSheet(actionStyle);
     connect(plusBtn, &QPushButton::clicked, this, [this] { emit joinRequested(); });
     fl->addWidget(plusBtn);
+    auto* helpBtn = new QPushButton(QStringLiteral("?"), footer);
+    helpBtn->setObjectName("messageFormattingHelpButton"); helpBtn->setFixedSize(34, 34);
+    helpBtn->setCursor(Qt::PointingHandCursor); helpBtn->setProperty("instantTooltip", true);
+    helpBtn->setToolTip(QCoreApplication::translate("ChatGui", "Message formatting"));
+    helpBtn->setAccessibleName(helpBtn->toolTip()); helpBtn->setStyleSheet(actionStyle + "font-size: 22px; font-weight: bold;");
+    fl->addWidget(helpBtn);
+    connect(helpBtn, &QPushButton::clicked, this, [this] {
+        auto* help = new QMessageBox(QMessageBox::Information, QCoreApplication::translate("ChatGui", "Message formatting"),
+            QCoreApplication::translate("ChatGui",
+                "**text** — bold\n"
+                "__text__ — italic\n"
+                "~~text~~ — strikethrough\n\n"
+                "Use paired tags on one line, without spaces next to the text.\n\n"
+                "Code blocks: put ``` on separate lines, as shown:\n"
+                "```cpp\n"
+                "int value = 42;\n"
+                "```\n\n"
+                "The language after ``` is optional: the chat will try to detect it.\n"
+                "Use ```text to disable highlighting. Copy copies the whole block."), QMessageBox::Ok, this);
+        help->setObjectName("messageFormattingHelp"); help->setAttribute(Qt::WA_DeleteOnClose);
+        help->setTextFormat(Qt::PlainText); help->setTextInteractionFlags(Qt::TextSelectableByMouse); help->open();
+        DEBUG_INFO(DEBUG_CATEGORY_CHAT, "message formatting help opened");
+    });
     DEBUG_DEBUG(DEBUG_CATEGORY_CHAT,
         "channel actions initialized icons=group-plus/enter icon_px=28 button=40x38 background=transparent tooltip_delay_ms=0");
     DEBUG_DEBUG(DEBUG_CATEGORY_CHAT, "connection monitor button initialized icon=diagnostics icon_px=24 button=34x34 tooltip_delay_ms=0");

tools/chatgui/translations/chatgui_en.ts

@@ -3,6 +3,11 @@
 <TS version="2.1" language="en_US" sourcelanguage="en_US">
 <context>
     <name>ChatGui</name>
+    <message><source>Message formatting</source><translation>Message formatting</translation></message>
+    <message>
+        <source>**text** — bold&#10;__text__ — italic&#10;~~text~~ — strikethrough&#10;&#10;Use paired tags on one line, without spaces next to the text.&#10;&#10;Code blocks: put ``` on separate lines, as shown:&#10;```cpp&#10;int value = 42;&#10;```&#10;&#10;The language after ``` is optional: the chat will try to detect it.&#10;Use ```text to disable highlighting. Copy copies the whole block.</source>
+        <translation>**text** — bold&#10;__text__ — italic&#10;~~text~~ — strikethrough&#10;&#10;Use paired tags on one line, without spaces next to the text.&#10;&#10;Code blocks: put ``` on separate lines, as shown:&#10;```cpp&#10;int value = 42;&#10;```&#10;&#10;The language after ``` is optional: the chat will try to detect it.&#10;Use ```text to disable highlighting. Copy copies the whole block.</translation>
+    </message>
     <message><source>Device group name</source><translation>Device group name</translation></message>
     <message><source>Could not rename device group</source><translation>Could not rename device group</translation></message>
     <message><source>Expand devices</source><translation>Expand devices</translation></message>

tools/chatgui/translations/chatgui_ru.ts

@@ -3,6 +3,11 @@
 <TS version="2.1" language="ru_RU" sourcelanguage="en_US">
 <context>
     <name>ChatGui</name>
+    <message><source>Message formatting</source><translation>Форматирование сообщений</translation></message>
+    <message>
+        <source>**text** — bold&#10;__text__ — italic&#10;~~text~~ — strikethrough&#10;&#10;Use paired tags on one line, without spaces next to the text.&#10;&#10;Code blocks: put ``` on separate lines, as shown:&#10;```cpp&#10;int value = 42;&#10;```&#10;&#10;The language after ``` is optional: the chat will try to detect it.&#10;Use ```text to disable highlighting. Copy copies the whole block.</source>
+        <translation>**текст** — жирный&#10;__текст__ — курсив&#10;~~текст~~ — зачёркнутый&#10;&#10;Ставьте парные теги в одной строке, без пробелов рядом с текстом.&#10;&#10;Блок кода: ``` должны быть на отдельных строках, как в примере:&#10;```cpp&#10;int value = 42;&#10;```&#10;&#10;Язык после ``` необязателен: чат попробует определить его сам.&#10;Укажите ```text для кода без подсветки. Copy копирует весь блок.</translation>
+    </message>
     <message><source>Device group name</source><translation>Имя группы устройств</translation></message>
     <message><source>Could not rename device group</source><translation>Не удалось переименовать группу устройств</translation></message>
     <message><source>Expand devices</source><translation>Развернуть устройства</translation></message>