Fix native-style Qt warning; add a few tooltips; trim Namespace hint text

Root cause of "QFont::setPointSize: Point size <= 0 (-1)" on some
dropdowns: the app never sets an explicit widget style, so it defaults to
native windowsvista, whose popup code calls setPointSize() on fonts
resolved from our QSS's pixel-based font-size (pointSize() is -1 by
design for px fonts). Tried app.setStyle("Fusion") first — silences it,
but Fusion doesn't render buttons/dropdowns to match the QSS the way the
native style does. Kept native style, filtered just that one message via
qInstallMessageHandler instead — it's cosmetic Qt console noise (the
rejected setPointSize call is a no-op, doesn't affect rendering), not a
real bug.

Also adds a handful of tooltips (Control Editor's Check Syntax/Cancel/
Create Control, device Configure dialog's Close, main toolbar's View/
Configure/RUN/LOG/Settings, a few Control Panel widgets) from an
in-progress app-wide tooltip pass, paused partway through by request —
remaining buttons are being done manually.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

6 files changed, 36 insertions, 3 deletions

diff --git a/main.py b/main.py
index dff00bd..26fcaaf 100644
--- a/main.py
+++ b/main.py
@@ -12,10 +12,30 @@ import sys, os
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
 from PyQt6.QtWidgets import QApplication
+from PyQt6.QtCore import qInstallMessageHandler, QtMsgType
 from ui.main_window import MainWindow
 
 
+def _qt_message_handler(msg_type, context, message):
+    """Silence one specific, harmless Qt warning: the native windowsvista
+    style's combo-box/menu popup code calls QFont::setPointSize() on a
+    pixel-sized font (our QSS uses px font-size, so pointSize() is -1 by
+    design) — cosmetic console noise only, doesn't affect rendering.
+    Everything else still prints normally."""
+    if "QFont::setPointSize" in message:
+        return
+    if msg_type == QtMsgType.QtWarningMsg:
+        print(f"Warning: {message}", file=sys.stderr)
+    elif msg_type == QtMsgType.QtCriticalMsg:
+        print(f"Critical: {message}", file=sys.stderr)
+    elif msg_type == QtMsgType.QtFatalMsg:
+        print(f"Fatal: {message}", file=sys.stderr)
+    else:
+        print(message, file=sys.stderr)
+
+
 def main():
+    qInstallMessageHandler(_qt_message_handler)
     app = QApplication(sys.argv)
     app.setApplicationName("LabUI")
 
diff --git a/ui/config_dialog.py b/ui/config_dialog.py
index 5a95821..cefee2d 100644
--- a/ui/config_dialog.py
+++ b/ui/config_dialog.py
@@ -45,6 +45,7 @@ class DeviceConfigDialog(QDialog):
         btn_row = QHBoxLayout()
         btn_row.addStretch()
         close_btn = QPushButton("Close")
+        close_btn.setToolTip("Close this dialog — use Apply & Reconnect on the Hardware tab first if you changed backend settings")
         close_btn.setDefault(True)
         close_btn.clicked.connect(self.accept)
         btn_row.addWidget(close_btn)
diff --git a/ui/control_editor.py b/ui/control_editor.py
index d167517..624e4c1 100644
--- a/ui/control_editor.py
+++ b/ui/control_editor.py
@@ -274,6 +274,7 @@ class ControlEditorDialog(QDialog):
         self._script_status = QLabel("")
         self._script_status.setObjectName("traceSource")
         check_btn = QPushButton("Check Syntax")
+        check_btn.setToolTip("Compile the script above and report any syntax error, without running it")
         check_btn.clicked.connect(self._check_script)
         btn_row = QHBoxLayout()
         btn_row.addWidget(self._script_status, 1)
@@ -287,8 +288,10 @@ class ControlEditorDialog(QDialog):
         div.setObjectName("devWindowDivider"); root.addWidget(div)
 
         btn_row = QHBoxLayout(); btn_row.addStretch()
-        cancel = QPushButton("Cancel"); cancel.clicked.connect(self.reject)
+        cancel = QPushButton("Cancel"); cancel.setToolTip("Discard changes and close")
+        cancel.clicked.connect(self.reject)
         ok     = QPushButton("Create Control")
+        ok.setToolTip("Save this control widget to the Control Panel")
         ok.setObjectName("applyButton"); ok.setDefault(True)
         ok.clicked.connect(self._on_ok)
         btn_row.addWidget(cancel); btn_row.addWidget(ok)
diff --git a/ui/control_panel.py b/ui/control_panel.py
index adf48e6..f0e18ef 100644
--- a/ui/control_panel.py
+++ b/ui/control_panel.py
@@ -252,6 +252,7 @@ class OnOffSwitch(ControlWidget):
 
         # Big toggle button
         self._btn = QPushButton("OFF")
+        self._btn.setToolTip("Toggle this output on/off")
         self._btn.setObjectName("switchBtn")
         self._btn.setCheckable(True)
         self._btn.setMinimumHeight(52)
@@ -338,12 +339,14 @@ class MotorControl(ControlWidget):
         btn_row = QHBoxLayout()
 
         self._dir_btn = QPushButton("▶  FWD")
+        self._dir_btn.setToolTip("Toggle motor direction (forward/reverse)")
         self._dir_btn.setObjectName("motorDirBtn")
         self._dir_btn.setCheckable(True)
         self._dir_btn.toggled.connect(self._on_dir)
         btn_row.addWidget(self._dir_btn)
 
         self._run_btn = QPushButton("START")
+        self._run_btn.setToolTip("Start/stop the motor at the speed set by the slider above")
         self._run_btn.setObjectName("motorRunBtnOff")
         self._run_btn.setCheckable(True)
         self._run_btn.toggled.connect(self._on_run)
@@ -410,6 +413,7 @@ class SetpointControl(ControlWidget):
         sp_lbl.setFixedWidth(24)
 
         self._minus_btn = QPushButton("−")
+        self._minus_btn.setToolTip(f"Decrease setpoint by {self.step} {self.unit}")
         self._minus_btn.setObjectName("spStepBtn")
         self._minus_btn.setFixedWidth(32)
         self._minus_btn.clicked.connect(self._decrement)
@@ -422,6 +426,7 @@ class SetpointControl(ControlWidget):
         self._sp_spin.valueChanged.connect(self._on_sp_changed)
 
         self._plus_btn = QPushButton("+")
+        self._plus_btn.setToolTip(f"Increase setpoint by {self.step} {self.unit}")
         self._plus_btn.setObjectName("spStepBtn")
         self._plus_btn.setFixedWidth(32)
         self._plus_btn.clicked.connect(self._increment)
diff --git a/ui/main_window.py b/ui/main_window.py
index 77f8286..19d4c69 100644
--- a/ui/main_window.py
+++ b/ui/main_window.py
@@ -188,6 +188,7 @@ class MainWindow(QMainWindow):
 
         # ── ⊞ View menu ───────────────────────────────────────────────────
         view_btn = QPushButton("⊞  View  ▾"); view_btn.setObjectName("toolbarSectionBtn")
+        view_btn.setToolTip("Show/hide the Control Panel and Namespace docks")
         self._view_menu = QMenu(self)
 
         self._act_ctrl_panel = QAction("Control Panel", self)
@@ -209,16 +210,19 @@ class MainWindow(QMainWindow):
         tb.addWidget(view_btn)
 
         config_btn = QPushButton("⚙  Configure"); config_btn.setObjectName("toolbarSectionBtn")
+        config_btn.setToolTip("Open Configuration — Devices, Channels, and Plot layout")
         config_btn.clicked.connect(lambda: self._open_config(0))
         tb.addWidget(config_btn)
 
         tb.addWidget(_sep())
 
         self._run_btn = QPushButton("▶  RUN")
+        self._run_btn.setToolTip("Start/stop acquisition")
         self._run_btn.setObjectName("runButton"); self._run_btn.setCheckable(True)
         self._run_btn.clicked.connect(self._toggle_run); tb.addWidget(self._run_btn)
 
         self._log_btn = QPushButton("⬤  LOG")
+        self._log_btn.setToolTip("Start/stop logging data to CSV (only available while running)")
         self._log_btn.setObjectName("logButton"); self._log_btn.setCheckable(True)
         self._log_btn.setEnabled(False); self._log_btn.clicked.connect(self._toggle_log)
         tb.addWidget(self._log_btn)
@@ -246,6 +250,7 @@ class MainWindow(QMainWindow):
         tb.addWidget(_sep())
 
         set_btn = QPushButton("⚙  Settings")
+        set_btn.setToolTip("App settings, theme, plugins")
         set_btn.setObjectName("toolbarSectionBtn"); set_btn.setCheckable(True)
         set_btn.clicked.connect(lambda c: self._open_settings())
         tb.addWidget(set_btn); self._btn_settings = set_btn
diff --git a/ui/namespace_panel.py b/ui/namespace_panel.py
index 2fcc7a1..7d8c42d 100644
--- a/ui/namespace_panel.py
+++ b/ui/namespace_panel.py
@@ -64,8 +64,7 @@ class NamespacePanel(QWidget):
         lay.setSpacing(0)
 
         hint = QLabel(
-            "Double-click a row to copy a ready-to-paste reference "
-            "(vars.get(...) or channels.get(...)) to the clipboard."
+            "Double-click a row to copy reference to clipboard"
         )
         hint.setObjectName("traceSource")
         hint.setWordWrap(True)