Game configurations: added 2 secret Sector_Set3dFloor flags. Shhh! Don't tell anybody!

Fixed source window freezing while Open Map window was open when opening a wad by dragging & dropping it on the editor's main window.
Image loading-related warnings and errors now display more information about the image resource.

Fixed, Script Editor: in some cases "[EP]" (Entry Position) markers were processed incorrectly when inserting a snippet.
Updated SharpCompress library to 0.11.5.
Updated ScintillaNET library to 3.6.3.

Added, Draw Ellipse mode: angle setting can now be changed using "Rotate Clockwise" and "Rotate Counterclockwise" actions.
Added, Draw Line and Draw Curve modes: added "Auto-finish drawing" setting. When enabled, the modes will automatically finish drawing when currently drawn lines and already existing level geometry form a closed shape.
Changed: sector-wise linedef flipping is now done using the new "Align Linedefs" action. "Flip Linedefs" action works the same as in DB2 again.
Changed: when a map was already loaded, using "Open Map" action will use that map's directory as the starting directory.
Changed: official IWADs can no longer be saved.
Changed: disabled lump ranges/duplicate entries checks for official IWADs.
Changed: wad type is now preserved when saving a map (previously all wads were saved as PWADs).
Changed: moved Updater.exe launch much closer to the editor termination point to avoid any chance of it closing the editor before it properly closes itself.
Updated ZDoom_DECORATE.cfg (A_Blast).
Updated documentation.

Changed, cosmetic: elapsed time is now displayed after resources loading finishes.
Changed, internal: changed Clock.CurrentTime type to long.
Fixed, Tag Statistics window: in some cases the map view was not updated after selecting items in Sectors/Linedefs/Things columns. 
Fixed, cosmetic: Draw Curve mode icon was missing a shadow.

Fixed, Map Analysis mode: fixed a crash when running "Check Polyobjects" check on a map without lines using "Polyobj_StartLine" action.
Updated ZDoom_linedefs.cfg (Line_SetPortalTarget).
Updated ZDoom_ACS.cfg (Line_SetPortalTarget).

Changed, Game configurations: "Polyobject Anchor" things should not trigger "Thing outside the map geometry" error in the Map Analysis mode.
Updated ZDoom_DECORATE.cfg (A_SetScale).

Added, Visual mode: both Sky1 and Sky2 MAPINFO properties are now used when creating classic skybox texture.

Fixed, ACS parser: the names of include files bundled with acc compiler should be also checked for duplicate includes from user scripts, unless those user scripts are libraries.

Fixed, Visual mode: in some cases GLDEFS glow effect was not updated after changing floor/ceiling texture.
Fixed, Draw Rectangle and Draw Ellipse modes: in some cases pressing "Reset" button did not update the shape preview.
Fixed, DB2 bug: sector geometry was not updated after undoing "Flip Sidedefs" action.

Fixed, Game configurations: Point Pusher (5001) and Point Puller (5002) things were missing from Boom configs.

Fixed, ACS parser: the names of include files bundled with acc compiler should be also checked for duplicate includes from user scripts.
Fixed, Script Editor: fixed another case when clicking a script error item didn't open/switch to the error source file.
Fixed, Update checker: fixed a crash when trying to check for update without active Internet connection.

Changed, Draw Ellipse mode: lowered minimum subdivisions to 3.
Fixed, Browse Action and Browse Effect windows: first option was always selected for any generalized action/effect parameter during generalized action/effect setup.

Changed, Draw Ellipse mode: Increase/Decrease bevel actions now always increase (and decrease) to the next even number.
Changed, Test Map drop-down: warning icon is now displayed when associated test engine executable can not be located, question icon is now displayed when the editor is unable to get the icon from the associated test engine executable.

Added, Draw Grid mode: "Lock slices to grid" now operates in 4 modes: "None", "Horizontal", "Vertical" and "Both". Can be helpful when drawing ladders and such.
Changed, all drawing modes: changeable drawing mode settings are now persistent.
Changed: "Dynamic grid size" mode is now disabled when changing grid size manually.
Documentation: "Command Line Parameters" topic contained a lot of incorrect information...
Updated ZDoom_DECORATE.cfg.

Fixed, Script Editor: fixed a crash when trying to open Script Editor in a Doom map format map.

Fixed, Custom Fields UI: in some cases mixed user var values were displayed incorrectly.

Fixed, Edit Linedefs window: textures on selected sidedefs must be updated when toggling "Replace unused textures" setting.
Fixed, Texture Selector control: in some cases actual textures were never loaded/displayed when "Replace unused textures" setting was disabled.
Fixed, Script Editor: auto-completion list is no longed displayed when editing comments, includes or strings.

Fixed, Edit Things window: thing type validation when editing multiple thing types was broken in r2527.

Fixed, DECORATE parser: quoted actor string properties (like RenderStyle) were processed incorrectly.
Fixed(?), Update checker: in some cases incorrect update check result was displayed.

Added, Linedef Edit window: added "Replace unused textures" checkbox. When disabled, textures on unused sidedef parts won't be replaced when changing textures. For example, you can now replace sidedef textures of the whole map at once without assigning middle textures to all double-sided sidedefs.
Updated documentation ("Compiling GZDoom Builder" - added "Quick start guide" section).
Updated ZDoom_DECORATE.cfg.

+A couple of cosmetic tweaks and fixes.
Updated ZDoom_DECORATE.cfg.

Fixed, Visual mode: fixed a crash, which happened after these steps: delete things in Classic mode -> undo things deletion in Visual mode -> redo things deletion in Visual mode.

Fixed: checking read-only flag of non-existing files is not a good idea... (fixes a bug introduced in r2520).
Updated ZDoom_DECORATE.cfg (min/max).
Documentation: fixed cosmetic formatting issues in "DECORATE keys" page.

Changed, Action arguments control: arguments are no longer reset to default values when changing action/thing type when old and new argument types and names are the same.

Updated ZDoom_DECORATE.cfg.
Updated documentation ("DECORATE keys" page).

Changed the way filtering in the Edit Things, Browse Action and Browse Effect windows work: items, which names start with filter text are now displayed first.
Cosmetic tweaks to the way thing bounding boxes are rendered in Things mode when "Fixed Things Scale" option is enabled (bounding boxes of highlighted/selected things are now more opaque than the ones of unselected things).
Changed, Preferences form: action selected in the actions list is now stays selected when applying the filtering (unless it's no longer valid).

Fixed, DB2 bug, Visual mode: in some cases (sidedef's sector ceiling lower than other side's sector floor) higher/lower sidedef picking was behaving incorrectly.

Added "Fixed Things Scale" setting (available in the View menu, as a button on the View toolbar and as the "Toggle Fixed Things Scale" action). When enabled, Things will no longer be scaled based on current zoom level in Classic modes, instead, thing bounding box will be drawn when appropriate (this option mimics DB1 things rendering style).
Internal: removed some remnants of fixed rendering pipeline from Renderer2D and Renderer3D.

Fixed, Visual mode: sector geometry was not updated after changing sector brightness under a 3D floor.

Added, DECORATE parser: damage types are now parsed.
Added: the editor now reports duplicate textures/flats/patches/sprites/colormaps/voxels in the loaded wads.
Added, all text parsers: added #region/#endregion support.
Added TERRAIN parser.
Added, Script Editor: added special handling for DECORATE special comments.
Added, Sector Edit window, UDMF: Soundsequence value was setup incorrectly when showing the window for multiple sectors with mixed Soundsequence value. 
Fixed, Map Options window: "Strictly load patches between P_START and P_END" was not applied when applying the changes.
Fixed, MAPINFO parser: MapInfo should be treated as defined when a map MAPINFO block corresponding to current map is encountered even if it doesn't define any properties recognized by the editor.
Fixed, all text parsers: in some cases error line was calculated incorrectly when reporting an error detected by a text parser.
Cosmetic: changed ' to " in the rest of Error and Warning messages.
Internal: added text resource tracking.
Updated ZDoom_DECORATE.cfg.
Updated documentation ("Game Configuration - Basic Settings" page).

Changed, Copy/Paste: the whole pasting operation is now aborted if the resulting number of sectors, linedefs, vertices or things exceeds map format's maximum.

Fixed, Map Options window: game configurations were checked in incorrect order when opening a map without a .dbs file.

Added, "Find Thing Action and Arguments" search mode: "Any action" (-1) can now be used as a search input.
Fixed, "Find Linedef Action and Arguments" and "Find Sector Effect" search modes: in some cases action/effect was checked incorrectly when performing a search.