The designer can be placed into any element on your page rather than filling the window, so it fits into an existing layout.

Designer setup. Configure the designer, load the report template, process its callbacks, and connect the save action to the application.
var designer = new Stimulsoft.Designer.StiDesigner(null, "StiDesigner", false);

var report = new Stimulsoft.Report.StiReport();
report.loadFile("../reports/SimpleList.mrt");

designer.report = report;
designer.renderHtml("content");   // id of the target element
Passing an element id to renderHtml draws the designer inside that element, so you can position and size it with your own HTML and CSS — embedding it in a panel, a tab or any part of the page.
На скриншоте ниже Вы можете увидеть результат выполнения данного кода:

Showing the Designer in a Required Position