Initially Hidden RadFileExplorer - appearance issues

Description

When RadFileExplorer is used in LightWeight render mode, it cannot recalculate all sizes when its parent is initially not visible, because browsers do not render dimensions for them. A common appearance glitch is that the contents of the treeview and/or the grid overflow the boundaries of the control.

Solution

You can:

• either switch to Classic render mode of the control,
• or invoke a full postback to add it to the page (do not use AJAX),
• or recalculate the size of the  nested controls of RadFileExplorer in a similar way:

<telerik:RadTabStrip runat="server" ID="rts1" MultiPageID="rmp1" Skin="Bootstrap" RenderMode="Lightweight" OnClientTabSelected="OnClientTabSelected">
    <Tabs>
        <telerik:RadTab Text="one"></telerik:RadTab>
        <telerik:RadTab Text="two"></telerik:RadTab>
    </Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage runat="server" ID="rmp1">
    <telerik:RadPageView runat="server" ID="rpv1" Selected="true">
        select the other tab with the file explorer
    </telerik:RadPageView>
    <telerik:RadPageView runat="server" ID="rpv2">
        <telerik:RadFileExplorer RenderMode="Lightweight" runat="server" ID="rfe1" Width="900px" Height="490px">
            <Configuration ViewPaths="~/" />
        </telerik:RadFileExplorer>
    </telerik:RadPageView>
</telerik:RadMultiPage>

function OnClientTabSelected(sender, args) {
    // check the currently active tab. This is just an example, the approach can be used with any other setup that shows the file explorer with JavaScript
    if (args.get_tab().get_text() == "two") {
        var fileExplorer = $find("<%=rfe1.ClientID%>");
        var toolbar = fileExplorer.get_toolbar();
        var splitter = fileExplorer.get_splitter();
        var grid = fileExplorer.get_grid();
        //calculate the height of any visible elements outside the splitter
        var toolbarHeight = $telerik.$(fileExplorer.get_toolbar().get_element()).height();
        var textBoxHeight = $telerik.$("#" + fileExplorer.get_addressBox()).height();
        //adjust for the height to take into account the visible elements
        var height = splitter.get_height() - toolbarHeight - textBoxHeight - 10;
        //use the current file explorer width
        var width = $telerik.$(fileExplorer.get_element()).width();

        setTimeout(function () {
            //resize and repaint controls
            grid.get_element().style.height = height + "px";
            grid.repaint();
            toolbar.repaint();
            splitter.resize(width, height);
            splitter.repaint();
        }, 10);
    }
}