What's New in
ReoGrid V4
16 major features — from lazy loading for 1M+ rows to full WPF parity, Excel-compatible formatting, conditional styles, and much more.
16
Major Features
1M+
Rows with Lazy Loading
WPF
Full Feature Parity
Excel
Format Compatibility
All New Features
A deep dive into every major feature and improvement shipped in ReoGrid V4.
Ultra-fast Data Loading
New Lazy Loading feature loads only the minimum required data initially, then streams in more as you scroll. Even 1 million rows render in a few hundred milliseconds.
// Set worksheet row count (e.g., 1 million rows)
worksheet.SetRows(1000000);
// Set data source in lazy loading mode
worksheet.AddDataSource(
new RangePosition(0, 0, 1000000, 10),
new MyDataSource(logs),
DataSourceLoadMode.LazyLoading
);Multi-row Headers
Column headers now support multiple rows with cell merging — perfect for category grouping and complex heading layouts.
var extensionHeader = worksheet.ExtensionColumnHeader;
extensionHeader.SetRowCount(3);
extensionHeader.MergeCells(0, 1, 2, 1);
extensionHeader[0, 1].Text = "Category";Major WPF Enhancements
Almost all features previously only available in WinForms are now fully supported in WPF — including dropdown lists, improved drawing speed, and stability on par with WinForms.
Flexible Data Source Mechanism
Bind and display data from databases, files, or APIs using the IDataSource<T> interface for any data type or structure.
var ds = new MyDataSource();
// Add data source to worksheet
sheet.AddDataSource("A1:G30", ds);Enhanced DropdownListCell
Dropdown lists now accept a worksheet cell range as the list source — enabling dynamic, real-time option selection from master data.
var myRange = sheet1.Ranges["G1:G3000"];
var dropdownList1 = new DropdownListCell(myRange);
sheet1.Cells["A1"].Body = dropdownList1;Excel-compatible Custom Formatting
Support for Excel-style custom format strings with colors, separators, and per-sign formatting for numbers, currency, and dates.
cell1.DataFormat = CellDataFormatFlag.Number;
cell1.DataFormatArgs = "#,##0;[Red]-#,##0";Enhanced Outline (Grouping)
Outline expand/collapse buttons can now appear above or below rows. The API also supports programmatic collapse and expand of all groups.
sheet.OutlineButtonLocation = OutlineButtonLocation.Top;
var outlineGroup = sheet.GetOutlineGroup(RowOrColumn.Row, 0);
outlineGroup.CollapseAll();
outlineGroup.ExpandAll();Drawing Performance Improvements
More precise visible-area detection, faster update checks, and minimized drawing delays for scrolling, selection, and editing — smooth even with millions of rows.
Custom Conditional Filters
Build flexible conditional filters programmatically — combine multiple conditions to powerfully filter worksheet data.
var filter = new ConditionalDataFilter();
var condition = new FilterCondition(
2, ConditionOperator.NotEquals, "USD");
filter.Conditions.Add(condition);
sheet.DoFilter("A1:G30", filter);Enhanced String Search
Workbook-wide keyword search with highlighting and next/previous navigation — ideal for quickly finding data in large datasets.
var session = new HighlightTextSearchSession(
Workbook, txtKeyword.Text,
Workbook.CurrentWorksheet);
session.Search();
session.MarkAllResultHighlight(SolidColor.Goldenrod);
session.NextMatch();Conditional Styles
Automatically apply styles based on cell values using formulas. Use THIS to reference the current cell value for dynamic visualization.
var rule1 = new Rule(
"THIS > 1000", "A1:Z30",
new WorksheetRangeStyle {
Flag = PlainStyleFlag.TextColor,
TextColor = SolidColor.Yellow,
});
sheet.ConditionalStyles.Add(rule1);Enhanced Cell Locking
Three-level locking — sheet, range, or individual cells. Fine-grained control for business forms and input-restricted applications.
// Lock all cells
sheet.IsLocked = true;
// Unlock only C5
sheet.Cells["C5"].IsLocked = CellLock.Unlocked;Floating Point Precision Correction
Automatically corrects minor floating-point errors — no more "3.00000000000004" in business calculations.
sheet.Options.FormulaCalculationPrecision =
FormulaCalculationPrecision.LowPrecision;WinAppDriver UI Testing
Official support for automated UI testing with WinAppDriver. Assign AutomationIds and run regression tests in code.
ReoGridControl.EnableUIAutomation = true;
var reoGrid = session
.FindElementByClassName("ReoGridControl");
reoGrid.Click();Zero-Row / Zero-Column Worksheets
Worksheets can now start completely empty (0 rows x 0 columns) and grow dynamically as data is added.
worksheet.SetRows(0);More Built-in Formulas
Expanded library of built-in functions and formulas for more complex and practical calculations — closer to full Excel parity.
What's New in the Latest v4.5 Release
Released June 12, 2026. Built around major formula upgrades and a fundamental overhaul of load performance and memory usage for large Excel files.
47 New Excel-Compatible Functions
IFERROR / SUMIFS / INDEX / TEXT, date & statistical functions, double-byte JIS / ASC, and more. Write multi-condition aggregation and error handling with the same formulas you use in Excel.
Point-Mode Formula Editing
Click and drag cells while editing to enter references. Move references with the arrow keys and see them color-coded and highlighted — the same feel as Excel.
XLSX Outline Import/Export
Round-trip row and column grouping (outlines) with Excel files. Set the expand/collapse button position independently for rows and columns.
Major Load Performance & Memory Gains
An in-house high-speed parser and lazy sheet loading cut memory usage by up to ~37% on a 10-million-cell workbook, and sped up cell loading by ~50%.
Licensing & Editions
Starting with V4, ReoGrid is offered as a commercial licensed product. ReoGrid V3 remains available as open-source under the MIT license.
Already using V3? See the V3 → V4 migration guide for the full list of compile-time breaks, behavior differences, and recommended new APIs.
Professional Edition
Up to 3 devices, 1 year of updates & technical support included
Enterprise Edition
Unlimited devices (site license), 1 year of updates & technical support included
Support Services
Every paid license includes a year of updates & technical support, with an optional annual renewal to keep it running. Hands-on development services are also available.
Technical Support
Usage consultation, sample code, troubleshooting and issue resolution — included with your license for the first year.
Development Support
Implementation proposals, customization, environment-specific support, and ongoing partnership via Slack.
Ready to upgrade to V4?
Get started with the latest features, performance improvements, and full WPF support.