Improve Login and Register page hinting

src/LoginPage.cpp

@@ -81,6 +81,14 @@ LoginPage::LoginPage(QWidget *parent)
         matrixid_input_ = new TextField(this);
         matrixid_input_->setLabel(tr("Matrix ID"));
         matrixid_input_->setPlaceholderText(tr("e.g @joe:matrix.org"));
+        matrixid_input_->setToolTip(
+          tr("Your login name. A mxid should start with @ followed by the user id. After the user "
+             "id you need to include your server name after a :.\nYou can also put your homeserver "
+             "address there, if your server doesn't support .well-known lookup.\nExample: "
+             "@user:server.my\nIf Nheko fails to discover your homeserver, it will show you a "
+             "field to enter the server manually."));
+        matrixid_input_->setValidator(
+          new QRegularExpressionValidator(QRegularExpression("@.+?:.{3,}"), this));
 
         spinner_ = new LoadingIndicator(this);
         spinner_->setFixedHeight(40);
@@ -97,13 +105,19 @@ LoginPage::LoginPage(QWidget *parent)
         password_input_ = new TextField(this);
         password_input_->setLabel(tr("Password"));
         password_input_->setEchoMode(QLineEdit::Password);
+        password_input_->setToolTip("Your password.");
 
         deviceName_ = new TextField(this);
         deviceName_->setLabel(tr("Device name"));
+        deviceName_->setToolTip(
+          tr("A name for this device, which will be shown to others, when verifying your devices. "
+             "If none is provided, a random string is used for privacy purposes."));
 
         serverInput_ = new TextField(this);
         serverInput_->setLabel("Homeserver address");
         serverInput_->setPlaceholderText("matrix.org");
+        serverInput_->setToolTip(tr("The address that can be used to contact you homeservers "
+                                    "client API.\nExample: https://server.my:8787"));
         serverInput_->hide();
 
         serverLayout_ = new QHBoxLayout();

src/RegisterPage.cpp

@@ -85,17 +85,26 @@ RegisterPage::RegisterPage(QWidget *parent)
 
         username_input_ = new TextField();
         username_input_->setLabel(tr("Username"));
+        username_input_->setValidator(
+          new QRegularExpressionValidator(QRegularExpression("[a-z0-9._=/-]+"), this));
+        username_input_->setToolTip(tr("The username must not be empty, and must contain only the "
+                                       "characters a-z, 0-9, ., _, =, -, and /."));
 
         password_input_ = new TextField();
         password_input_->setLabel(tr("Password"));
         password_input_->setEchoMode(QLineEdit::Password);
+        password_input_->setToolTip(tr("Please choose a secure password. The exact requirements "
+                                       "for password strength may depend on your server"));
 
         password_confirmation_ = new TextField();
         password_confirmation_->setLabel(tr("Password confirmation"));
         password_confirmation_->setEchoMode(QLineEdit::Password);
 
         server_input_ = new TextField();
-        server_input_->setLabel(tr("Home Server"));
+        server_input_->setLabel(tr("Homeserver"));
+        server_input_->setToolTip(
+          tr("A server that allows registration. Since matrix is decentralized, you need to first "
+             "find a server you can register on or host your own."));
 
         form_layout_->addWidget(username_input_, Qt::AlignHCenter, nullptr);
         form_layout_->addWidget(password_input_, Qt::AlignHCenter, nullptr);

src/ui/TextField.cpp

@@ -147,7 +147,10 @@ QColor
 TextField::underlineColor() const
 {
         if (!underline_color_.isValid()) {
-                return QPalette().color(QPalette::Highlight);
+                if (hasAcceptableInput() || !isModified())
+                        return QPalette().color(QPalette::Highlight);
+                else
+                        return Qt::red;
         }
 
         return underline_color_;