Tabs and windows

SumatraPDF opens documents in tabs inside one window, or in separate windows. Which you get depends on two independent settings, UseTabs and ReuseInstance, plus optional command-line flags.

By default files open as tabs in the running SumatraPDF window.

Tabs: UseTabs = true opens new documents as tabs
Single instance: ReuseInstance = true sends files from Explorer or the command line to the running process
Switch tabs: Ctrl + Tab (Smart Tab Switch), Ctrl + PageDown / Ctrl + PageUp, Alt + 1 to Alt + 9
New window: Ctrl + Shift + N, or -new-window / -new-window-tabs on the command line
Session restore: RestoreSession = true reopens last session’s tabs

Open documents in tabs #

Set both in advanced settings (Settings → Advanced Settings…):

UseTabs = true: new documents open as tabs in an existing window
ReuseInstance = true: files opened from Explorer or the command line go to the running process

Both default to true. UseTabs needs a restart, and ReuseInstance takes effect on the next file open.

Fix: tabs enabled but new window every time #

If UseTabs = true but ReuseInstance = false, each file is opened by a new process, so you always get a separate window. Tabs only apply within one process.

Fix: set ReuseInstance = true and restart SumatraPDF.

Every file opening a new window is the most frequent tabs question on the forum.

Open a document in a new window #

Shortcut: Ctrl + Shift + N opens the current document in a new window
Command-line: -new-window opens each file in a new window even when UseTabs = true (ver 3.2+)
Command-line: -new-window-tabs opens one new window with all files as tabs (ver 3.7+)

See the flags table under Reference.

Switch tabs #

See Keyboard shortcuts:

Ctrl + Tab / Ctrl + Shift + Tab: next / previous tab (ver 3.6+: opens the Smart Tab Switch list while you hold Ctrl, and switches when you release). It works the same way as the browser tab switcher
Ctrl + PageDown / Ctrl + PageUp: next / previous tab in tab-strip order, immediately, without the switcher popup (CmdNextTab / CmdPrevTab)
Alt + 1 to Alt + 8, and Alt + 9 (last tab): jump to a tab by number
Command Palette: @ to switch tabs by name

Smart Tab Switch list, shown while Ctrl is held

Hide the caption #

Press Shift + F8, choose View → Show Caption, or run CmdToggleCaption in the Command Palette to show or hide the caption (ver 3.7+). Hiding it gives the document more space. Move the mouse to the top edge to reveal the caption, including its tabs, menu and window buttons, as an overlay. It disappears when the mouse moves away. The document stays the same size while the overlay is visible.

The choice is saved as ShowCaption, which defaults to true. You can also change it in Advanced Settings. Keep UseTabs = true to continue opening documents in tabs. Custom commands can force a state with CmdToggleCaption on or CmdToggleCaption off.

In 3.5 and earlier, Ctrl + Tab / Ctrl + Shift + Tab switched tabs immediately in tab-strip order (no overlay list). In 3.6+ those keys run Smart Tab Switch (CmdNextTabSmart / CmdPrevTabSmart), which shows a tab list while Ctrl is held.

To get the old behavior (useful when flicking quickly between two documents):

Setting (ver 3.7+, simplest): set CtrlTabSimple = true. Ctrl + Tab / Ctrl + Shift + Tab then switch immediately in tab-strip order. Set it back to false to get the switcher back.
Shortcut: use Ctrl + PageDown / Ctrl + PageUp instead.
Rebind: rebind the keys in advanced settings so Ctrl + Tab runs plain next/prev tab:

Shortcuts [
    [
        Cmd = CmdNextTab
        Key = Ctrl + Tab
    ]
    [
        Cmd = CmdPrevTab
        Key = Ctrl + Shift + Tab
    ]
]

Note: TabsMru only changes the order of tabs inside the Smart Tab Switch list (most-recently-used vs strip order). It does not hide the switcher. Use CtrlTabSimple or the rebind above for that.

Close a tab #

Shortcut: Ctrl + W or q

Open another Home tab #

Click + after the last tab, or press Ctrl + K, then New Tab (CmdNewTab) in Command Palette (ver 3.7+). The cursor is in its filter box, so you can start typing to filter your history. A file you open from it replaces it, instead of opening in a new tab. You can drag it to another position in the tab bar and close it like a document tab. It is not reopened by RestoreSession.

With NoHomeTab = true it works the same, including in an empty window, so opening a file leaves no Home tab behind.

Show or hide the Home tab #

When UseTabs = true, an empty window may show a Home tab.

Setting: NoHomeTab = true skips it
Close it when other tabs are open, and reopen it with Ctrl + K, then Go To Home Page in Command Palette

Reopen tabs on startup #

With RestoreSession = true, SumatraPDF reopens tabs (and window positions) from the last session on startup. See How we store settings.

Note: -for-testing deliberately skips session restore and does not save settings.

Tips #

If every file opens a new window despite UseTabs = true, set ReuseInstance = true.
Use Ctrl + PageDown / Ctrl + PageUp to switch tabs without the switcher popup.
Use @ to find a tab by name when many are open.
Use -new-window-tabs to open a batch of files together in their own window.

Reference #

Settings #

Setting	Default	What it does
`UseTabs`	`true`	New documents open as tabs in an existing window instead of always spawning a new window
`ReuseInstance`	`true`	Opening a file from Explorer or the command line reuses an already running SumatraPDF process

Setting	Restart required?
`ReuseInstance`	No, takes effect on the next file open
`UseTabs`	Yes, close and restart SumatraPDF

You can also change ReuseInstance and UseTabs at runtime (ver 3.7+) via Ctrl + K, Advanced Settings... in Command Palette (CmdAdvancedSettings). Changing UseTabs affects new windows only. Switching between tabbed and non-tabbed layout for an existing window may still need a restart.

Command-line flags #

Flag	Effect
`-new-window`	Open each file in a new window even when `UseTabs = true` (ver 3.2+). Several files: one window per file
`-new-window-tabs`	Open one new window and load all files as tabs in that window (ver 3.7+)
`-reuse-instance`	Send the file to an already running instance (mainly for DDE and scripts). For normal use, prefer the `ReuseInstance` setting

-reuse-instance is not needed for everyday double-click opening when ReuseInstance = true.

Multiple instances #

If several SumatraPDF processes are already running (for example because ReuseInstance = false), the behavior of -reuse-instance is undefined, and the file may go to any instance.

To force a single instance, keep ReuseInstance = true and close extra windows.