Troubleshooting

This page covers runtime problems: the EA compiles, but the UI does not show, does not respond, does not repaint, or leaves objects behind.

For compiler errors, see Common compile errors.

The panel does not appear

Most likely causes

g_ui.Init(...) failed.
SetRoot(...) was not called.
The UI tree was created but not attached.
The EA was attached to the wrong chart/subwindow.
The chart object prefix conflicts with another EA.
There is a runtime error in OnInit() before the UI is built.

Fix

Start from the minimum root pattern.

MuiRoot g_ui;

int OnInit()
{
  if(!g_ui.Init(ChartID(),0,"MyUI_",512,16))
    return(INIT_FAILED);

  MuiPage *page=new MuiPage();
  page.Title("Demo");
  g_ui.SetRoot(page);

  EventSetMillisecondTimer(16);
  return(INIT_SUCCEEDED);
}

Check the Experts tab for errors.

How to verify

Compile and attach a supplied example such as:

Experts/ModernUI/Examples/BasicPanel.mq5

If a supplied example works, the issue is probably in your EA setup.

The panel appears but does not respond

Most likely cause

OnChartEvent() is not forwarded into MuiRoot.

Fix

Add this to the EA:

void OnChartEvent(const int id,const long &lparam,const double &dparam,const string &sparam)
{
  g_ui.OnChartEvent(id,lparam,dparam,sparam);
}

How to verify

Click a button in a supplied example. If it responds there but not in your EA, compare the event forwarding.

The panel does not repaint or update reliably

Most likely cause

OnTimer() is not forwarded into MuiRoot, or the timer is not set.

Fix

Add the timer in OnInit():

EventSetMillisecondTimer(16);

Forward OnTimer():

void OnTimer()
{
  g_ui.OnTimer();
}

How to verify

Use a demo that updates labels, toasts, or status rows and confirm the UI updates after interaction.

Text boxes or native inputs remain on the chart after removing the EA

Most likely cause

g_ui.Shutdown() is missing from OnDeinit().

Native text hosts may use MT5 chart objects such as OBJ_EDIT. Shutdown lets ModernUI remove those objects cleanly.

Fix

void OnDeinit(const int reason)
{
  g_ui.Shutdown();
}

How to verify

Attach an example with a text box, remove it from the chart, and confirm no input objects remain.

Controls are visible but disabled or not clickable

Possible causes

A parent container is disabled.
A modal/dialog/drawer overlay is receiving input first.
A control is covered by another overlay element.
The control is outside a clipped scroll area.
The chart event is not reaching the root.

Fix

Check:

Parent visibility/enabled state.
Whether a modal or drawer is open.
Whether OnChartEvent() is forwarded.
Whether the control is inside a scroll/clipped container.

Hover or focus visuals look stale

Possible causes

A custom control paints outside its PaintBounds().
A handler changes a visual state without invalidating.
Code requested layout/paint in the wrong order.
A partial invalidation region is too small.

Fix

For normal controls, call:

control.Refresh();

For geometry changes, use:

control.Relayout();

If you built a custom control that paints outside its layout rect, adjust its paint bounds.

Atlas icons do not appear

Most likely cause

The optional atlas PNGs are not installed under MQL5/Images/ModernUI.

Fix

Copy this package folder:

Images/ModernUI/

To:

MQL5/Images/ModernUI/

The UI should still work without these files because ModernUI falls back to canvas-drawn icons.

Large lists or tables feel slow

Possible causes

Expensive work in BindRow.
Expensive work in CellText.
Rebuilding the UI tree too often.
Calling Relayout() on frequent value changes that did not move geometry.
Using simple helpers for large dynamic datasets.

Fix

Use source-backed virtualized controls for large data and keep row binding cheap.

See:

A trade-style example does not place trades

This is expected.

ModernUI trade-style examples are UI-only unless your own EA adds broker logic.

They do not place, modify, or close real orders.

Still stuck?

Create a minimal reproduction and include the details listed in Reporting a bug.