Demo: Added extra demo in the Basic Horizontal Layout section. (#1977) + PR guidelines

ImFontAtlas::AddFontDefault: Made it possible to override glyph ranges. (#1965)

Examples: imgui_impl_osx: Fix for incorrect DeltaTime calculation on mac OS. (#1978)

Examples: OpenGL3: Tweaks, added changelog. (#1941)

Examples; imgui_impl_opengl3.cpp to work with Emscripten (#1941) ...

* Add some ifdefs to add emscripten specific params and includes

* Update imgui_impl_opengl3.cpp

* Update imgui_impl_opengl3.cpp

* Update imgui_impl_opengl3.cpp

* replace __EMSCRIPTEN_BUILD__ with __EMSCRIPTEN__

* replace GLFW_INCLUDE_ES3 with direct header

* removing useless glfw include

* Making call to glPolygonMode() optional

CollapseButton: Added hovering highlight + minor consistency tweaks.

Internals: Drag and Drop: default drop preview use a narrower clipping rectangle (no effect here, but other branches uses a narrow clipping rectangle that was too small so this is a fix for it) + Comments

Internals: Changed SplitterBehavior() signature to be consistent with other similar signatures. (#319).

Internals: Extracted part of Begin into UpdateWindowParentAndRootLinks(). Useful to call to keep state updated immediately (namely useful for docking) + small tidying up of imgui_internal.h

Assert that fmt != NULL before calling vsnprintf (#1969) ...

In the case of Visual Studio 15.6 + Windows SDK 10.0, vsnprintf() with NULL format string appears to corrupt the stack...

Internals: Child windows that are clipped or part of a collapsed parent are not marked as collapsed anymore, but just a separate hidden marker set. We distinguish hiding for size measurement vs hiding for other reasons. Cleaned a little the end of Begin.

Nav: Tweaked CTRL+TAB to hide visual noise on fast switch + fading out screen dimming and highlight to make the experience less harsh

FAQ update

Internals: SplitterBehavior() added hover_visibility_delay parameter which is helpful to reduce visual noise. (#319)

Made it possible to move a window by dragging from the Collapse button (past the drag threshold). Extracted some code out to a CollapseButton() function.

Internals: Renamed one of the arrow functions so their name don't collide.

Examples: Using fully qualified "Dear ImGui" name in window titles.

Fixed horizontal mouse wheel not forwarding the request to the parent window if ImGuiWindowFlags_NoScrollWithMouse is set. (#1463, #1380, #1502)

Internals: Extracted part of NewFrame() into a UpdateMouseWheel() function.

Added asserts to catch illegal modifications of the font atlas between NewFrame() and EndFrame()/Render(). (#1958)

Changed ImGui::GetTime() return value from float to double to avoid accumulating floating point imprecisions over time.

Readme: fixed typo + patron

Ignore GCC warning (-Wclass-memaccess) in imgui.h (#1959)

Tweaked Contributing guidelines, Issue and PR templates

ImGuiTextFilter, TextRange: removed cruft from TextRange since it's not a publicly and generic helper at the moment + marked internal stuff + changed a reference to a pointer. (#1879)

Examples: SDL: Removed SDL_HAS_WARP_MOUSE_GLOBAL in the non-viewport branch. (#1954) (+1 squashed commits)

Nav: Fixed CTRL+TAB windowing list from always showing the implicit Debug window. (#787)

Fix warning when IMGUI_DEFINE_MATH_OPERATORS is already defined by build system. (#1950)

Demo: Clarified the use of IsItemHovered()/IsItemActive() right after being in the "Active, Focused, Hovered & Focused Tests" section. This will be of more importance with the introduction of tabs.

Demo: Fixed spacing from b629f90 change.